Diagnostic Trouble Code (DTC) P2231, P2232, P2234 or P2235
DTC Descriptor
DTC P2231 : HO2S Signal Circuit Shorted to Heater Circuit Bank 1 Sensor 1
DTC P2232 : HO2S Signal Circuit Shorted to Heater Circuit Bank 1 Sensor 2
DTC P2234 : HO2S Signal Circuit Shorted to Heater Circuit Bank 2 Sensor 1
DTC P2235 : HO2S Signal Circuit Shorted to Heater Circuit Bank 2 Sensor 2
Diagnostic Fault Information
Perform the Diagnostic System Check prior to using this diagnostic procedure.
Circuit Description
The engine control module (ECM) supplies a voltage near 450 mV between the heated oxygen sensor (HO2S) high signal circuit and the low reference circuit. The HO2S varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean. The ECM monitors and stores the HO2S voltage information. The ECM evaluates the HO2S voltage samples in order to determine the amount of time that the HO2S voltage was out of range. The ECM compares the stored HO2S voltage samples taken within each sample period and determines if the majority of the samples are out of the operating range.
Conditions for Running the DTC
- DTCs P0030, P0031, P0032, P0050, P0051 and P0052 ran and passed.
- The HO2S heater control is enabled
Conditions for Setting the DTC
- The internal HO2S signal voltage switches at the same rate as the heater circuit.
- The HO2S heater control is enabled
- The ECM internal sensing element resistance is greater than 570 Ω.
- The ECM detects the internal HO2S signal voltage is 1.47 – 1.53 V.
- The HO2S is at operating temperature.
Action Taken When the DTC Sets
DTCs P2231, P2232 ,P2234 and P2235 are Type E DTCs.
Conditions for Clearing the DTC
DTCs P2231, P2232 ,P2234 and P2235 are Type E DTCs.
Circuit/System Verification
- Ignition ON, observe the appropriate HO2S voltage parameter. The HO2S voltage parameter should be less than 1,050 mV.
- If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector of the appropriate HO2S.
- Ignition ON, verify that the HO2S parameter is between 350-500 mV.
- If more than 500 mV, test the signal circuit of the HO2S sensor for a short to the heater circuit. If the circuit/connections test normal, replace the ECM.
- If all circuits/connections test normal, replace the applicable HO2S.
Diagnostic Trouble Code (DTC) P2237, P2238, P2239, P2240, P2241, or P2242
DTC Descriptor
DTC P2237 : HO2S Pumping Current Control Circuit Bank 1 Sensor 1
DTC P2238 :HO2S Pumping Current Control Circuit Low Voltage Bank 1 Sensor 1
DTC P2239 :HO2S Pumping Current Control Circuit High Voltage Bank 1 Sensor 1
DTC P2240 : HO2S Pumping Current Control Circuit Bank 2 Sensor 1
DTC P2241 :HO2S Pumping Current Control Circuit Low Voltage Bank 2 Sensor 1
DTC P2242 :HO2S Pumping Current Control Circuit High Voltage Bank 2 Sensor 1
Diagnostic Fault Information
Perform the Diagnostic System Check prior to using this diagnostic procedure.
Circuit/System Description
The wide band heated oxygen sensor (HO2S) measures the amount of oxygen in the exhaust system and provides more information than the switching style HO2S. The wide band sensor consists of an oxygen sensing cell, an oxygen pumping cell, and a heater. The exhaust gas sample passes through a diffusion gap between the sensing cell and the pumping cell. The engine control module (ECM) supplies a voltage to the HO2S and uses this voltage as a reference to the amount of oxygen in the exhaust system. An electronic circuit within the ECM controls the pump current through the oxygen pumping cell in order to maintain a constant voltage in the oxygen sensing cell. The ECM monitors the voltage variation in the sensing cell and attempts to keep the voltage constant by increasing or decreasing the amount of current flow, or oxygen ion flow, to the pumping cell. By measuring the amount of current required to maintain the voltage in the sensing cell, the ECM can determine the concentration of oxygen in the exhaust. The HO2S voltage is displayed as a lambda value. A lambda value of 1 is equal to a stoichiometric air fuel ratio of 14.7:1. Under normal operating conditions, the lambda value will remain around 1. When the fuel system is lean, the oxygen level will be high and the lambda signal will be high or more than 1. When the fuel system is rich, the oxygen level will be low, and the lambda signal will be low or less than 1. The ECM uses this information to maintain the correct air/fuel ratio.
Conditions for Running the DTC
DTC P2237, P2238, P2239, P2240, P2241, or P2242
- The ignition voltage is between 10-16 volts.
- The engine is operating in closed loop.
- The HO2S heater is at operating temperature.
- The ECM is commanding the lambda more than 1.03 or less than 0.97
- The ECM is commanding decel fuel cut-off for more than 3 seconds
- The ECM is commanding the lambda rich and then lean periodically with a change of more than 2 percent.
Conditions for Setting the DTC
P2238 and P2241
The ECM detects that the HO2S Pumping Current Trim Circuit voltage is low.
P2239 and P2242
The ECM detects that the HO2S Pumping Current Trim Circuit voltage is high.
P2237 and P2240
The ECM detects that the H02S Pumping Current Trim Circuit voltage is not within a predetermined range.
Action Taken when the DTC Sets
DTC P2237, P2238, P2239, P2240, P2241 or P2242 are type E DTCs.
Conditions for Clearing the MIL/DTC
DTC P2237, P2238, P2239, P2240, P2241 or P2242 are type E DTCs.
Circuit/System Verification
- Allow the engine to reach operating temperature. Engine running, observe the affected HO2S parameter with a scan tool.
- The HO2S 1 value should vary from below 200 mV to above 800 mV and respond to fuelling changes.
- The HO2S 2 value should change more than 200 mV when the throttle is quickly cycled 3 times from Closed to wide open and back to Closed after running the engine at 1,500 RPM for 30 seconds.
- If any HO2S heater DTCs are set, diagnose those DTCs first.
- The affected HO2S may be damaged due to contamination. Prior to replacing the affected HO2S, inspect for the following sources of contamination:
Circuit/System Testing
- Disconnect the affected HO2S.
- Ignition ON install a 3A fusible link wire between the low reference voltage and the a low reference circuit.
- Connect a DMM between the input pump current circuit and a known ground. If the voltage is not 1 volt test the for a short to ground, short to voltage or an open/high resistance. If circuit test normal replace the ECM.
- If all circuit test normal then replace the affected H02S sensor.
Diagnostic Trouble Code (DTC) P2243 or P2247
DTC Descriptor
DTC P2243 : HO2S Reference Voltage Circuit Bank 1 Sensor 1
DTC P2247 :HO2S Reference Voltage Circuit Bank 2Sensor 1
Diagnostic Fault Information
Perform the Diagnostic System Check prior to using this diagnostic procedure.
Circuit/System Description
The heated oxygen sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the engine is started the control module operates in an Open Loop mode, ignoring the HO2S signal voltage while calculating the air/fuel ratio. The control module supplies the HO2S with a reference or bias voltage of about 450 mV. While the engine runs the HO2S heats up and begins to generate a voltage within a range of 0–1,000 mV. This voltage will fluctuate above and below the bias voltage. Once sufficient HO2S voltage fluctuation is observed by the control module, Closed Loop is entered. The control module uses the HO2S voltage to determine the air/fuel ratio. An HO2S voltage that increases above bias voltage toward 1,000 mV indicates a rich fuel mixture. An HO2S voltage that decreases below bias voltage toward 0 mV indicates a lean fuel mixture.
The heating elements inside each HO2S heat the sensor to bring the sensor up to operating conditions faster.
This allows the system to enter Closed Loop earlier and the control module to calculate the air/fuel ratio sooner.
Conditions for Running the DTC
DTC P2243 and P2247
- The ignition voltage is between 10-16 volts.
- The engine is operating.
Conditions for Setting the DTC
DTC P2243 and P2247
The ECM detects that the H02S reference voltage circuit is low.
Action Taken when the DTC Sets
DTCs P2243 and P2247 are type E DTCs.
Conditions for Clearing the DTC
DTCs P2243 and P2247 are type E DTCs.
Circuit/System Verification
- Allow the engine to reach operating temperature. Engine running, observe the affected HO2S parameter with a scan tool.
- The HO2S 1 value should vary from below 200 mV to above 800 mV and respond to fuelling changes.
- The HO2S 2 value should change more than 200 mV when the throttle is quickly cycled 3 times from Closed to wide open and back to Closed after running the engine at 1,500 RPM for 30 seconds.
- If any HO2S heater DTCs are set, diagnose those DTCs first.
- The affected HO2S may be damaged due to contamination. Prior to replacing the affected HO2S, inspect for the following sources of contamination:
Circuit/System Testing
- Disconnect the affected HO2S.
- Measure for approximately 450 mV from the affected HO2S reference voltage circuit terminal and a known ground.
- If more than approximately 450 mV, test the affected HO2S reference voltage circuit for a short to voltage. If the circuit tests normal, replace the control module.
- If less than approximately 450 mV, test the affected HO2S high signal circuit for high resistance. If the circuit tests normal, replace the control module.
- Install a 3A fusible link wire between the affected HO2S reference voltage circuit terminal and the affected HO2S low signal circuit terminal. The affected HO2S parameter should indicate 0 mV.
- If not 0 mV and all circuits and connectors test normal, replace the control module.
- Install a test lamp between the affected HO2S reference voltage circuit terminal and battery voltage. The affected HO2S parameter should indicate approximately 1,095 mV.
- If not 1,095 mV and all circuits and connectors test normal, replace the control module.
- If the control module and all circuits test normal, replace the affected HO2S.
Diagnostic Trouble Code (DTC) P2251 or P2254
DTC Descriptor
DTC P2251 :HO2S Low Reference Circuit bank 1 Sensor 1
DTC P2254 :HO2S Low Reference Circuit Bank 2 Sensor 1
Diagnostic Fault Information
Perform the Diagnostic System Check prior to using this diagnostic procedure.
Circuit/System Description
The heated oxygen sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the engine is started the control module operates in an Open Loop mode, ignoring the HO2S signal voltage while calculating the air/fuel ratio. The control module supplies the HO2S with a reference or bias voltage of about 450 mV. While the engine runs the HO2S heats up and begins to generate a voltage within a range of 0–1,000 mV. This voltage will fluctuate above and below the bias voltage. Once sufficient HO2S voltage fluctuation is observed by the control module, Closed Loop is entered. The control module uses the HO2S voltage to determine the air/fuel ratio. An HO2S voltage that increases above bias voltage toward 1,000 mV indicates a rich fuel mixture. An HO2S voltage that decreases below bias voltage toward 0 mV indicates a lean fuel mixture.
The heating elements inside each HO2S heat the sensor to bring the sensor up to operating conditions faster.
This allows the system to enter Closed Loop earlier and the control module to calculate the air/fuel ratio sooner.
Conditions for Running the DTC
DTC P2251,or P2254
- The ignition voltage is between 10-16 volts.
- The engine is operating.
Conditions for Setting the DTC
DTC P2251 or P2254
The ECM detects that the HO2S low reference circuit is low.
Action Taken when the DTC Sets
DTC P2251,or P2254 are type E DTCs.
Conditions for Clearing the DTC
DTC P2251,or P2254 are type E DTCs.
Circuit/System Verification
- Allow the engine to reach operating temperature. Engine running, observe the affected HO2S parameter with a scan tool.
- The HO2S 1 value should vary from below 200 mV to above 800 mV and respond to fuelling changes.
- The HO2S 2 value should change more than 200 mV when the throttle is quickly cycled 3 times from Closed to wide open and back to Closed after running the engine at 1,500 RPM for 30 seconds.
- If any HO2S heater DTCs are set, diagnose those DTCs first.
- The affected HO2S may be damaged due to contamination. Prior to replacing the affected HO2S, inspect for the following sources of contamination.
Circuit/System Testing
- Disconnect the affected HO2S.
- Install a 3A fusible link wire between the Low reference signal circuit and the a low reference return circuit.
- If voltage does not read 1 V. test the circuit for short or open/high resistance. If circuit test normal replace the ECM.
- If the control module and all circuits test normal, replace the affected HO2S.
Diagnostic Trouble Code (DTC) P2270 or P2272
DTC Descriptor
DTC P2270 : HO2S Signal Stuck Lean Bank 1 Sensor 2
DTC P2272 : HO2S Signal Stuck Lean Bank 2 Sensor 2
Diagnostic Fault Information
Perform the Diagnostic System Check prior to using this diagnostic procedure.
Circuit Description
The engine control module (ECM) supplies a voltage near 450 mV between the heated oxygen sensor (HO2S) high signal circuit and the low reference circuit. The HO2S varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean. The ECM monitors and stores the HO2S voltage information. The ECM evaluates the HO2S voltage samples in order to determine the amount of time that the HO2S voltage was out of range. The ECM compares the stored HO2S voltage samples taken within each sample period and determines if the majority of the samples are out of the operating range.
Conditions for Running the DTC
- DTCs P0036, P0037, P0038, P0056, P0057, P0058, P0137, P0138, P0140, P0141, P0157, P0158, P0160, P0161, P0342, P0343, P0366, P0367, P0368, P0443, P0451, P0452, P0453, P0458 and P0459 ran and passed.
- The engine is running.
- The HO2S 2 are at operating temperature for longer than 10 seconds.
- The long term fuel control is enabled.
Conditions for Setting the DTC
- When the ECM detects the HO2S 2 is less than 650 mV for 100 seconds, the ECM enriches the fuel mixture up to 30 percent for 10 seconds. This DTC sets if the ECM detects the HO2S 2 is still less than 650 mV.
- The engine is running.
- The HO2S 2 are at operating temperature for longer than 10 seconds.
- The long term fuel control is enabled.
Action Taken When the DTC Sets
DTCs P2270 and P2272 are Type E DTCs.
Conditions for Clearing the DTC
DTCs P2270 and P2272 are Type E DTCs.
Circuit/System Verification
- Ignition ON, observe the DTC information with a scan tool. Verify that DTCs P0137, P0138, P0140, P0157, P0158, or P0160 are not set.
- If any of the listed DTCs are set, refer to the appropriate DTC information for further diagnosis.
- Operate the engine above 1,200 RPM for 30 seconds, observe the HO2S voltage parameter. The reading should fluctuate above and below the range of 350-550 mV.
- If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.
Circuit/System Testing
- Engine operating, move the related HO2S harnesses for the appropriate rear sensor between the HO2S harness connector and the engine control module (ECM) while monitoring the appropriate HO2S voltage parameter. Verify that the HO2S parameter does not change abruptly while moving the related harnesses.
- If the HO2S parameter does change abruptly while moving the related harnesses repair the circuit as necessary.
- Ignition OFF, disconnect the harness connector of the appropriate HO2S.
- Ignition ON, verify that the HO2S parameter is between 350-500 mV.
- If less than 350 mV, test the signal circuit of the HO2S sensor for a short to ground. If the circuit/connections test normal, replace the ECM.
- Verify that none of the following conditions exist :
- Lean fuel injectors
- Water intrusion in the HO2S harness connector
- Low fuel system pressure
- Fuel that is contaminated
- The vacuum hoses for splits, kinks, and proper connection
- The air intake system after the mass air flow (MAF) sensor for vacuum leaks
- Exhaust system leaks
- Contaminated HO2S – Silicon
- An engine mechanical condition.
- If you find any of the above conditions, repair as necessary.
- If all circuits/connections test normal, replace the applicable HO2S.
Diagnostic Trouble Code (DTC) P2271 or P2273
DTC Descriptor
DTC P2271 : HO2S Signal Stuck Rich Bank 1 Sensor 2
DTC P2273 : HO2S Signal Stuck Rich Bank 2 Sensor 2
Diagnostic Fault Information
Perform the Diagnostic System Check prior to using this diagnostic procedure.
Circuit Description
The engine control module (ECM) supplies a voltage near 450 mV between the heated oxygen sensor (HO2S) high signal circuit and the low reference circuit. The HO2S varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean. The ECM monitors and stores the HO2S voltage information. The ECM evaluates the HO2S voltage samples in order to determine the amount of time that the HO2S voltage was out of range. The ECM compares the stored HO2S voltage samples taken within each sample period and determines if the majority of the samples are out of the operating range.
Conditions for Running the DTC
- DTCs P0036, P0037, P0038, P0056, P0057, P0058, P0137, P0138, P0140, P0141, P0157, P0158, P0160, P0161, P0342, P0343, P0366, P0367, P0368, P0443, P0451, P0452, P0453, P0458 and P0459 ran and passed
- The engine is running
- The HO2S 2 are at operating temperature for longer than 10 seconds.
- The long term fuel control is enabled.
Conditions for Setting the DTC
- When the ECM detects the HO2S 2 is greater than 650 mV for 100 seconds, the ECM leans the fuel mixture up to -7 percent for 10 seconds. If this signal voltage is still greater than 650 mV, the ECM tests the HO2S at the next decel fuel cut-off. This DTC sets if the ECM detects the HO2S 2 signal voltage is greater than 200 mV after 4 seconds in decel fuel cut-off mode.
Action Taken When the DTC Sets
DTCs P2271 and P2273 are Type E DTCs.
Conditions for Clearing the DTC
DTCs P2271 and P2273 are Type E DTCs.
Circuit/System Verification
- Ignition ON, observe the DTC information with a scan tool. Verify that DTCs P0137, P0138, P0140, P0157, P0158, or P0160 are not set.
- If any of the listed DTCs are set, refer to the appropriate dTC informationfor further diagnosis.
- Operate the engine above 1,200 RPM for 30 seconds, observe the HO2S voltage parameter. The reading should fluctuate above and below the range of 350-550 mV.
- If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.
Circuit/System Testing
- Engine operating, move the related HO2S harnesses for the appropriate rear sensor between the HO2S harness connector and the engine control module (ECM) while monitoring the appropriate HO2S voltage parameter. Verify that the HO2S parameter does not change abruptly while moving the related harnesses.
- If the HO2S parameter does change abruptly while moving the related harnesses repair the circuit as necessary.
- Ignition OFF, disconnect the harness connector of the appropriate HO2S.
- Ignition ON, verify that the HO2S parameter is between 350-500 mV.
- If more than 500 mV, test the signal circuit of the HO2S sensor for a short to voltage. If the circuit/connections test normal, replace the ECM.
- Verify that none of the following conditions exist :
- Rich fuel injectors
- Water intrusion in the HO2S harness connector
- High fuel system pressure
- Fuel that is contaminated
- A collapsed air intake duct
- A restricted air filter element
- Exhaust system restrictions
- Excessive fuel in the crankcase
- An engine mechanical condition.
- If you find any of the above conditions, repair as necessary.
- If all circuits/connections test normal, replace the applicable HO2S.
Diagnostic Trouble Code (DTC) P2297 or P2298
DTC Descriptor
DTC P2297 : HO2S Performance During Decel Fuel Cut-Off (DFCO) Bank 1 Sensor 1
DTC P2298 : HO2S Performance During Decel Fuel Cut-Off (DFCO) Bank 2 Sensor 1
Diagnostic Fault Information
Perform the Diagnostic System Check prior to using this diagnostic procedure.
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
HO2S Bank 1 Sensor 1 Signal | P0131 | P0130, P0134 | P0132 | P0130, P0133 |
HO2S Bank 1 Sensor 2 Signal | P0137 | P0136, P0140 | P0138 | P0136, P0139 |
HO2S Bank 2 Sensor 1 Signal | P0151 | P0150, P0154 | P0152 | P0150, P0153 |
HO2S Bank 2 Sensor 2 Signal | P0157 | P0156, P0160 | P0158 | P0156, P0159 |
Low Reference | - | P0130, P0136, P0150, P0156 | P0134, P0140, P0154, P0160 | - |
Circuit/System Description
The wide band heated oxygen sensor (HO2S) measures the amount of oxygen in the exhaust system and provides more information than the switching style HO2S. The wide band sensor consists of an oxygen sensing cell, an oxygen pumping cell, and a heater. The exhaust gas sample passes through a diffusion gap between the sensing cell and the pumping cell. The engine control module (ECM) supplies a voltage to the HO2S and uses this voltage as a reference to the amount of oxygen in the exhaust system. An electronic circuit within the ECM controls the pump current through the oxygen pumping cell in order to maintain a constant voltage in the oxygen sensing cell. The ECM monitors the voltage variation in the sensing cell and attempts to keep the voltage constant by increasing or decreasing the amount of current flow, or oxygenion flow, to the pumping cell. By measuring the amount of current required to maintain the voltage in the sensing cell, the ECM can determine the concentration of oxygen in the exhaust. The HO2S voltage is displayed as a lambda value. A lambda value of 1 is equal to a stoichiometric air fuel ratio of 14.7:1. Under normal operating conditions, the lambda value will remain around 1. When the fuel system is lean, the oxygen level will be high and the lambda signal will be high or more than 1. When the fuel system is rich, the oxygen level will be low, and the lambda signal will be low or less than 1. The ECM uses this information to maintain the correct air/fuel ratio.
Conditions for Running the DTC
P2297, P2298
- The ignition voltage is between 10-16 volts.
- The engine is operating.
- The front heated oxygen sensors are at operating temperature.
- The internal ECM HO2S signal voltage is less than 4.81 volts.
- A decel fuel cut-off has occurred 10 times with successful adjustments.
Conditions for Setting the DTC
P2297, P2298
The ECM detects that the internal HO2S signal voltage is more than 3.7 volts for more than 10 seconds or the ECM detects that the compensation factor of the HO2S is less than -25 percent or more than 30 percent of the expected value.
Action Taken When the DTC Sets
DTCs P2297 and P2298 are type E DTCs.
Conditions for Clearing the MIL/DTC
DTCs P2297 and P2298 are type E DTCs.
Circuit/System Verification
- Engine idling, observe the appropriate HO2S voltage parameter. The reading should fluctuate above and below the range of 350-550 mV.
- If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the appropriate HO2S sensor.
- Ignition ON, verify that the HO2S parameter is between 350-500 mV.
- If less than 350 mV, test the signal circuit for a short to ground. If the circuit/connections test normal, replace the ECM.
- If greater than 500 mV, test the signal circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
- Ignition OFF, test for 5 ohms or less between the low reference circuit of the HO2S sensor and a known ground.
- If greater than 5 ohms, test the low reference circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.
- Install a 3A fusible link wire between the signal circuit and the low reference circuit of the HO2S sensor and verify the HO2S sensor parameter is less than 60 mV.
- If greater than 60 mV, test the signal circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.
- If all circuits/connections test normal, replace the HO2S sensor.
Diagnostic Trouble Code (DTC) P2626, P2627, P2628, P2629, P2630, or P2613
DTC Descriptor
DTC P2626 : HO2S Pumping Current Trim Circuit Bank 1 Sensor 1
DTC P2627 : HO2S Pumping Current Trim Circuit Low Voltage Bank 1 Sensor 1
DTC P2628 : HO2S Pumping Current Trim Circuit High Voltage Bank 1 Sensor 1
DTC P2629 : HO2S Pumping Current Trim Circuit Bank 2 Sensor 1
DTC P2630 : HO2S Pumping Current Trim Circuit Low Voltage Bank 2 Sensor 1
DTC P2631 : HO2S Pumping Current Trim Circuit High Voltage Bank 2 Sensor 1
Diagnostic Fault Information
Perform the Diagnostic System Check prior to using this diagnostic procedure.
Circuit/System Description
The wide band heated oxygen sensor (HO2S) measures the amount of oxygen in the exhaust system and provides more information than the switching style HO2S. The wide band sensor consists of an oxygen sensing cell, an oxygen pumping cell, and a heater. The exhaust gas sample passes through a diffusion gap between the sensing cell and the pumping cell. The engine control module (ECM) supplies a voltage to the HO2S and uses this voltage as a reference to the amount of oxygen in the exhaust system. An electronic circuit within the ECM controls the pump current through the oxygen pumping cell in order to maintain a constant voltage in the oxygen sensing cell. The ECM monitors the voltage variation in the sensing cell and attempts to keep the voltage constant by increasing or decreasing the amount of current flow, or oxygen ion flow, to the pumping cell. By measuring the amount of current required to maintain the voltage in the sensing cell, the ECM can determine the concentration of oxygen in the exhaust. The HO2S voltage is displayed as a lambda value. A lambda value of 1 is equal to a stoichiometric air fuel ratio of 14.7:1. Under normal operating conditions, the lambda value will remain around 1. When the fuel system is lean, the oxygen level will be high and the lambda signal will be high or more than 1. When the fuel system is rich, the oxygen level will be low, and the lambda signal will be low or less than 1. The ECM uses this information to maintain the correct air/fuel ratio.
Conditions for Running the DTC
DTC P2237, P2238, P2239, P2240, P2241, or P2242
- The ignition voltage is between 10-16 volts.
- The engine is operating in closed loop.
- The HO2S heater is at operating temperature.
- The ECM is commanding the lambda more than 1.03 or less than 0.97.
- The ECM is commanding decel fuel cut-off for more than 3 seconds.
- The ECM is commanding the lambda rich and then lean periodically with a change of more than 2 percent.
Conditions for Setting the DTC
P2627 and P2630
The ECM detects that the HO2S Pumping Current Trim Circuit voltage is low.
P2628 and P2631
The ECM detects that the HO2S Pumping Current TrimCircuit voltage is high.
P2626 and P2629
The ECM detects that the H02S Pumping Current Trim Circuit voltage is not within a predetermined range.
Action Taken When the DTC Sets
DTC P2126, P2627, P2628, P2629, P2630 and P2613 are type E DTCs.
Conditions for Clearing the MIL/DTC
DTC P2126, P2627, P2628, P2629, P2630 and P2613 are type E DTCs.
Circuit/System Verification
- Allow the engine to reach operating temperature. Engine running, observe the affected HO2S parameter with a scan tool.
- The HO2S 1 value should vary from below 200 mV to above 800 mV and respond to fuelling changes.
- The HO2S 2 value should change more than 200 mV when the throttle is quickly cycled 3 times from Closed to wide open and back to Closed after running the engine at 1,500 RPM for 30 seconds.
- If any HO2S heater DTCs are set, diagnose those DTCs first.
- The affected HO2S may be damaged due to contamination. Prior to replacing the affected HO2S, inspect for the following sources of contamination.
Circuit/System Testing
- Disconnect the affected HO2S.
- Ignition ON install a 3A fusible link wire between the low reference voltage and the a low reference circuit.
- Connect a DMM between the input pump current circuit and a known ground. If the voltage is not 1 volt test the for a short to ground, short to voltage or an open/high resistance. If circuit test normal replace the ECM.
- If all circuit test normal then replace the affected H02S sensor.
Diagnostic Trouble Code (DTC) U0001
DTC Descriptor
DTC U0001 : High Speed CAN Communication Bus
Circuit/System Description
The engine control module (ECM) communicates directly with the control modules connected to the GM LAN serial data communication circuit through the GM LAN protocol.
DTC U0001 sets if the ECM detects a fault condition in the serial data communication circuit.
Conditions for Running the DTC
The ignition voltage is 10.0 - 16.0 V.
The vehicle power mode requires serial data communication.
Conditions for Setting the DTC
The ECM detects a specified number of transmitted messages are not valid.
Conditions for Clearing the DTC
The Serial Data Communication Circuit DTCs are Type C DTCs.
DTC U0001 Diagnostic Table
| Step | Action | Value(s) | Yes | No |
| 1 | Has the Diagnostic System Check been performed? | - | Go to Step 2 | Go to "Diagnostic System Check" |
| 2 | - Switch off the ignition for 30 seconds.
- Operate the vehicle within the conditions for running the DTC.
- Using the Scan Tool, select the DTC display function.
Does DTC U0001 fail this ignition cycle? | - | Go to Step 3 | - |
| 3 | Replace the ECM. Was the repair completed? | - | Go to Step 4 | - |
| 4 | - Using the Scan Tool, clear the DTCs.
- Switch off the ignition for 30 seconds.
- Start the engine.
- Operate the vehicle within the conditions for running the DTC.
Does DTC U0001 fail this ignition cycle? | - | Go to Step 2 | Go to Step 5 |
| 5 | Using the Scan Tool, select the DTC display function. Are there any DTCs displayed? | - | Go to the appropriate DTC Table | System OK |
Diagnostic Trouble Code (DTC) U0101 or U0121
DTC Descriptor
Note : The symptom byte may not be displayed on a scan tool.
DTC U0101 : Lost Communication with TCM
DTC U0121 :Lost Communication With Anti-Lock Brake System (ABS) Control Module
Circuit/System Description
Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.
Conditions for Running the DTC
Conditions for Setting the DTC
- No signal from corresponding CAN node
- A key message from TCM node is not received
- The ECM detects that the validity information from both the left and the right driven wheels is received as invalid
Action Taken When the DTC Sets
- DTC U0101 and U0121 are type C DTCs.
Conditions for Clearing the MIL/DTC
- DTC U0101 and U0121 are type C DTCs.
Diagnostic Aids
- A poor connection at the inoperative module may cause this code to set.
- An improperly powered module may cause this code to set.
- If there are multiple non-communicating modules choose the one closest to the data link connector (DLC). Some modules may not have internal protection for specific voltage outputs and may open a battery positive voltage or ignition voltage source fuse. If a voltage input fuse is open and no short is found in that circuit, ensure that no module output voltage circuit is shorted to ground before replacing the module. This diagnostic can be used for any module that should communicate with high or low speed GMLAN serial data providing the vehicle is equipped with the option that uses that module.
DTC U0101 or U0121 Diagnostic Table
| Step | Action | Value(s) | Yes | No |
| 1 | Did you perform the Diagnostic System Check? | - | Go to Step 2 | Go to "Diagnostic System Check" |
| 2 | Test the following circuits of the module that is not communicating for an open or a short to ground: - The battery positive voltage input circuits
- The battery positive voltage output circuits
- The ignition voltage input circuits
- The ignition voltage output circuits
- The switched battery positive voltage circuits
Did you find and correct the condition? | - | Go to Step 7 | Go to Step 3 |
| 3 | - Turn OFF the ignition.
- Test the ground circuits of the module that is not communicating for an open.
Did you find and correct the condition? | - | Go to Step 7 | Go to Step 4 |
| 4 | Test the high speed GMLAN serial data circuits of the module that is not communicating for an open. Did you find and correct the condition? | - | Go to Step 7 | Go to Step 5 |
| 5 | Inspect the harness connectors of the module that is not communicating for poor connections and terminal tension at the following circuits: - The battery positive voltage input circuits
- The battery positive voltage output circuits
- The ignition voltage input circuits
- The ignition voltage output circuits
- The switched battery positive voltage supply circuits
- The ground circuits
- The high speed GMLAN serial data circuits
Did you find and correct the condition? | - | Go to Step 7 | Go to Step 6 |
| 6 | Replace the module that is not communicating. Did you complete the replacement? | - | Go to Step 7 | - |
| 7 | - Clear the DTCs with a scan tool.
- Turn OFF the ignition for 30 seconds.
- Start the engine.
- Operate the vehicle within the Conditions for Setting the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition? | - | Go to Step 2 | Go to Step 8 |
| 8 | Check if any additional DTCs are set. Are there any DTCs that have not been diagnosed? | - | Go to applicable DTC table | System OK |
Diagnostic Trouble Code (DTC) U0402
Circuit Descriptor
DTC U0402 : Invalid Data Received From Body Control Module
The transmission control module (TCM) sends transmission data to the engine control module (ECM). The data is sent to the ECM through a communication network called the GM local area network (LAN). Two circuits are used to communicate LAN data between the ECM and TCM. A fault in the LAN will not cause DTC U0402 to set by itself. If a LAN fault occurs, other DTCs will set in addition to DTC U0402.
If the ECM receives invalid transmission data from the TCM, this DTC sets.
Conditions for Running the DTC
Conditions for Setting the DTC
- The ECM receives no valid transmission data from the TCM.
Action Taken When the DTC Sets
Conditions for Clearing the MIL/DTC
DTC U0402 Diagnostic Table
| Step | Action | Value(s) | Yes | No |
| 1 | Did you perform the Diagnostic System Check? | - | Go to Step 2 | Go to "Diagnostic System Check" |
| 2 | - Turn the ignition switch to LOCK.
- Install a scan tool to the data link connector (DLC).
- Turn the ignition switch to ON.
- Observe DTC information with a scan tool.
Did any DTCs display other than U0442? | - | Go to applicable DTC table | Go to Step 3 |
| 3 | - Clear the DTC Information with a scan tool.
- Turn the ignition OFF for at least 30 seconds.
- Start, and allow the engine to idle.
Did DTC U0402 fail this ignition? | - | Go to Step 7 | Go to "Intermittent" |
| 4 | Did any transmission control module (TCM) DTCs or any other "U" DTC also set? | - | Go to applicable DTC table | Go to Step 5 |
| 5 | Test the LAN circuits in the wiring harness between TCM and the ECM for a high resistance or a poor connection at the module connectors. Did you find and correct the condition? | - | Go to Step 7 | Go to Step 6 |
| 6 | Replace the ECM. Did you complete the replacement? | - | Go to Step 7 | - |
| 7 | - Clear the DTCs with a scan tool.
- Turn OFF the ignition for 30 seconds.
- Start the engine.
- Operate the vehicle within the Conditions for Setting the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition? | - | Go to Step 2 | Go to Step 8 |
| 8 | Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | - | Go to applicable DTC table | System OK |
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