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Diagnostic Trouble Code (DTC) P0112, P0113

DTC Description

DTC P0112 : Intake Air Temperature (IAT) Sensor Circuit Low Voltage
DTC P0113 : Intake Air Temperature (IAT) Sensor Circuit High Voltage

Circuit/System Description

The intake air temperature (IAT) sensor is a variable resistor. The IAT sensor has a signal circuit and a low reference circuit. The IAT sensor measures the temperature of the air entering the engine. The engine control module (ECM) supplies 5 volts to the IAT signal circuit, and a ground for the IAT low reference circuit. When the IAT sensor is cold, the sensor resistance is high. When the air temperature increases, the sensor resistance decreases. With high sensor resistance, the ECM detects a high voltage on the IAT signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the IAT signal circuit.

Conditions for Running the DTC

(P0112)
(P0113)

Conditions for Setting the DTC

P0112
P0113

Action Taken When the DTC Sets

Refer to “Diagnostic Trouble Code (DTC) Type Definitions”

Conditions for Clearing the MIL/DTC

Refer to “Diagnostic Trouble Code (DTC) Type Definitions”

Diagnostic Aids

DTC P0112, P0113

Step Action Value(s) Yes No
1
Did you perform the Diagnostic System Check?
-
Go to Step 2
Go to "Diagnostic System Check"
2
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running 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 3
Go to "Intermittent Conditions".
3
Observe the IAT Sensor parameter with a scan tool.
Is the IAT Sensor parameter greater than the specified value?
138°C
Go to Step 4
Go to Step 5
4
Test the IAT sensor signal circuit for a short to ground.
Did you find and correct the condition?
-
Go to Step 11
Go to Step 5
5
  1. Install a 3-amp fused jumper wire between the IAT sensor signal circuit and the low reference circuit.
  2. Turn the ignition switch ON.
  3. Observe the scan tool IAT sensor parameter.
Is the parameter less than the specified value?
-45°C
Go to Step 6
Go to Step 7
6
Test the IAT sensor signal circuit for a short to voltage, an open, or high resistance.
Did you find and correct the condition?
-
Go to Step 11
Go to Step 7
7
  1. Turn the ignition switch OFF.
  2. Allow sufficient time for the ECM to power down.
  3. Disconnect the harness connector at the IAT sensor.
  4. Measure the resistance between the IAT sensor low reference circuit and ground.
Is the resistance greater than the specified value?
5 ohms
Go to Step 8
Go to Step 10
8
Test the IAT sensor low reference circuit for an open or high resistance.
Did you find and correct the condition?
-
Go to Step 11
Go to Step 9
9
Replace the IAT sensor.
Did you complete the replacement?
-
Go to Step 11
-
10
Replace the ECM.
Did you complete the replacement?
-
Go to Step 11
-
11
  1. Clear the DTCs with the scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running 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 12
12
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) P0117, P0118

DTC Description

DTC P0117 : Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage
DTC P0118 : Engine Coolant Temperature (ECT) Sensor Circuit High Voltage

Circuit/System Description

The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 volts to the ECT signal circuit, and a ground for the ECT low reference circuit. When the ECT is cold, the sensor resistance is high. When the ECT increases, the sensor resistance decreases. With high sensor resistance, the ECM detects a high voltage on the ECT signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the ECT signal circuit.

Conditions for Running the DTC

(P0117)
Or,
(P0118)
Or,

Conditions for Setting the DTC

P0117
P0118

Action Taken When the DTC Sets

Refer to “Diagnostic Trouble Code (DTC) Type Definitions”

Conditions for Clearing the MIL/DTC

Refer to “Diagnostic Trouble Code (DTC) Type Definitions”

Diagnostic Aids

DTC P0117, P0118

Step Action Value(s) Yes No
1
Did you perform the Diagnostic System Check?
-
Go to Step 2
Go to "Diagnostic System Check"
2
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running 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 3
Go to "Intermittent Conditions".
3
Observe the ECT Sensor parameter with a scan tool.
Is the ECT Sensor parameter greater than the specified value?
140°C
Go to Step 4
Go to Step 5
4
Test the ECT sensor signal circuit for a short to ground.
Did you find and correct the condition?
-
Go to Step 11
Go to Step 5
5
  1. Install a 3-amp fused jumper wire between the ECT sensor signal circuit and the low reference circuit.
  2. Turn the ignition switch ON.
  3. Observe the scan tool ECT sensor parameter.
Is the parameter less than the specified value?
-40°C
Go to Step 6
Go to Step 7
6
Test the ECT sensor signal circuit for a short to voltage, an open, or high resistance.
Did you find and correct the condition?
-
Go to Step 11
Go to Step 7
7
  1. Turn the ignition switch OFF.
  2. Allow sufficient time for the ECM to power down.
  3. Disconnect the harness connector at the ECT sensor.
  4. Measure the resistance between the ECT sensor low reference circuit and ground.
Is the resistance greater than the specified value?
5 ohms
Go to Step 8
Go to Step 10
8
Test the ECT sensor low reference circuit for an open or high resistance.
Did you find and correct the condition?
-
Go to Step 11
Go to Step 9
9
Replace the ECT sensor.
Did you complete the replacement?
-
Go to Step 11
-
10
Replace the ECM.
Did you complete the replacement?
-
Go to Step 11
-
11
  1. Clear the DTCs with the scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running 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 12
12
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) P0122, P0123, P0222, P0223, P2135

DTC Description

DTC P0122 : Throttle Position (TP) Sensor 1 Circuit Low Voltage
DTC P0123 : Throttle Position (TP) Sensor 1 Circuit High Voltage
DTC P0222 : Throttle Position (TP) Sensor 2 Circuit Low Voltage
DTC P0223 : Throttle Position (TP) Sensor 2 Circuit High Voltage
DTC P2135 : Throttle Position (TP) Sensor 1-2 Correlation

Circuit Description

The throttle body assembly contains 2 throttle position (TP) sensors. The TP sensors are mounted to the throttle body assembly and are not serviceable. The TP sensors provide a signal voltage that changes relative to throttle plate angle. The engine control module (ECM) supplies the TP sensors with a common 5-volt reference circuit, a common low reference circuit, and 2 independent signal circuits.
The TP sensors have opposite functionality. TP sensor 1 signal voltage increases from below 1 volt at idle to above 4 volts at wide open throttle (WOT). TP sensor 2 signal voltage decreases from above 4 volts at idle to below 1 volt at WOT.

Conditions for Running the DTC

Conditions for Setting the DTC

(P0122)
(P0123)
(P0222)
(P0223)
(P2135)

Action Taken When the DTC Sets

Refer to “Diagnostic Trouble Code (DTC) Type Definitions”

Conditions for Clearing the MIL/DTC

Refer to “Diagnostic Trouble Code (DTC) Type Definitions”

Diagnostic Aids

DTC P0122, P0123, P0222, P0223, P2135

Step Action Value(s) Yes No
1
Did you perform the Diagnostic System Check?
-
Go to Step 2
Go to "Diagnostic System Check"
2
  1. Turn the ignition OFF.
  2. Disconnect the wiring harness connector from the throttle body.
  3. Turn the ignition ON.
  4. Using a DMM, measure the voltage between the 5V reference circuit of the TP sensor 1 and a good ground.
Is the voltage within the specified value?
4.8 - 5.2 V
Go to Step 3
Go to Step 10
3
Using a DMM, measure the voltage between the 5V reference circuit and the low reference circuit of the TP sensor 1.
Is the voltage within the specified value?
4.8 - 5.2 V
Go to Step 4
Go to Step 11
4
  1. Turn the ignition ON, with the engine OFF.
  2. With a scan tool, observe the TP sensor 1 parameter.
Does the scan tool indicate that the TP sensor parameter is less than the specified value?
0.3 V
Go to Step 5
Go to Step 12
5
  1. Turn the ignition OFF.
  2. Connect a fused jumper wire between the 5V reference circuit and the signal circuit of the TP sensor 1.
  3. Turn the ignition ON, with the engine OFF.
  4. With a scan tool, observe the TP sensor 1 parameter.
Does the scan tool indicate that the TP sensor parameter is within the specified value?
4.8 - 5.2 V
Go to Step 6
Go to Step 13
6
  1. Turn OFF the ignition.
  2. Remove the fused jumper wire.
  3. Using a DMM, measure the voltage between the 5V reference circuit of the TP sensor 2 and a good ground.
Is the voltage within the specified value?
4.8 - 5.2 V
Go to Step 7
Go to Step 14
7
Using a DMM, measure the voltage between the 5V reference circuit and the low reference circuit of the TP sensor 2.
Is the voltage within the specified value?
4.8 - 5.2 V
Go to Step 8
Go to Step 15
8
  1. Turn the ignition ON, with the engine OFF.
  2. With a scan tool, observe the TP sensor 2 parameter.
Does the scan tool indicate that the TP sensor parameter is less than the specified value?
0.3 V
Go to Step 9
Go to Step 16
9
  1. Turn the ignition OFF.
  2. Connect a fused jumper wire between the 5V reference circuit and the signal circuit of the TP sensor 2.
  3. Turn the ignition ON, with the engine OFF.
  4. With a scan tool, observe the TP sensor 2 parameter.
Does the scan tool indicate that the TP sensor parameter is within the specified value?
4.8 - 5.2 V
Go to Step 18
Go to Step 17
10
Check the 5V reference circuit of the TP sensor 1 for the following conditions:
  • Short to voltage
  • Short to ground
  • Open
  • High resistance
Did you find and correct the condition?
-
Go to Step 20
Go to Step 19
11
Check the low reference circuit of the TP sensor 1 for the following conditions:
  • Short to voltage
  • Open
  • High resistance
Did you find and correct the condition?
-
Go to Step 20
Go to Step 19
12
Check the signal circuit of the TP sensor 1 for the following condition:
  • Short to voltage
Did you find and correct the condition?
-
Go to Step 20
Go to Step 19
13
Check the signal circuit of the TP sensor 1 for the following conditions:
  • Short to ground
  • Open
  • High resistance
Did you find and correct the condition?
-
Go to Step 20
Go to Step 19
14
Check the 5V reference circuit of the TP sensor 2 for the following conditions:
  • Short to voltage
  • Short to ground
  • Open
  • High resistance
Did you find and correct the condition?
-
Go to Step 20
Go to Step 19
15
Check the low reference circuit of the TP sensor 2 for the following conditions:
  • Short to voltage
  • Open
  • High resistance
Did you find and correct the condition?
-
Go to Step 20
Go to Step 19
16
Check the signal circuit of the TP sensor 2 for the following condition:
  • Short to voltage
Did you find and correct the condition?
-
Go to Step 20
Go to Step 19
17
Check the signal circuit of the TP sensor 2 for the following conditions:
  • Short to ground
  • Open
  • High resistance
Did you find and correct the condition?
-
Go to Step 20
Go to Step 19
18

Note : The TP sensor is not serviceable.
Replace the throttle body assembly.
Did you complete the replacement?
-
Go to Step 20
-
19
Replace the ECM.
Did you complete the replacement?
-
Go to Step 20
-
20
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running 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 21
21
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) P0131, P0132, P0134, P0137, P0138, P013A, P013B, P0140

DTC Description

DTC P0131 : HO2S Circuit Low Voltage Sensor 1
DTC P0132 : HO2S Circuit High Voltage Sensor 1
DTC P0134 : HO2S Circuit Insufficient Activity Sensor 1
DTC P0137 : HO2S Circuit Low Voltage Sensor 2
DTC P0138 : HO2S Circuit High Voltage Sensor 2
DTC P013A :HO2S Slow Response Rich to Lean Sensor 2
DTC P013B :HO2S Slow Response Lean to Rich Sensor 2
DTC P0140 : HO2S Circuit Insufficient Activity Sensor 2

Circuit Description

The heated oxygen sensors (HO2S) are used for fuel control and post 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-to-fuel ratio. The control module supplies the HO2S with a reference, or bias voltage of approximately 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-to-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-to-fuel ratio sooner.

Conditions for Running the DTC

Conditions for Setting the DTC

(P0131)
(P0132)
(P0134)
(P0137)
(P0138)
(P013A)
(P013B)
(P0140)

Action Taken When the DTC Sets

Refer to “Diagnostic Trouble Code (DTC) Type Definitions”

Conditions for Clearing the MIL/DTC

Refer to “Diagnostic Trouble Code (DTC) Type Definitions”

Diagnostic Aids

Normal scan tool voltage varies between 0.1volts and 0.9 volts while in closed loop.
Inspect the oxygen sensor wire. The oxygen sensor may be positioned incorrectly and contacting the exhaust manifold.
Check for an intermittent ground in the wire between the oxygen sensor and the engine control module.
Perform an injector balance test to determine if a restricted fuel injector may be causing the lean condition.
Vacuum of crankcase leaks will cause a lean running condition.
An exhaust manifold gasket leak of a cracked exhaust manifold may cause outside air to be pulled into the exhaust and past the sensor.

DTC P0131, P0132, P0134, P0137, P0138, P013A, P013B, P0140

Step Action Value(s) Yes No
1
Did you perform the Diagnostic System Check?
-
Go to Step 2
Go to "Diagnostic System Check"
2
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running 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 3
Go to "Intermittent Conditions".
3
  1. Turn OFF the ignition.
  2. Disconnect the wiring harness connector of the applicable heated oxygen sensor (HO2S).
  3. Start the engine.
  4. Observe the HO2S voltage parameter with a scan tool.
Is the voltage within the specified range?
350 ~ 550 mV
Go to Step 5
Go to Step 4
4
Is the voltage above the specified range?
350 ~ 550 mV
Go to Step 9
Go to Step 8
5
  1. Turn OFF the ignition.
  2. Using a DMM, measure the resistance between the low reference circuit of the HO2S and ground.
Is the resistance less than the specified value?
5 Ohms
Go to Step 6
Go to Step 11
6
  1. Connect a fused jumper wire between the signal circuit and low reference circuit of the wiring harness connector of the HO2S.
  2. Start the engine.
  3. Observe the HO2S voltage parameter with a scan tool.
Is the voltage less than the specified value?
60 mV
Go to Step 7
Go to Step 10
7
Test or inspect for the following conditions:
  • Lean or rich fuel injectors.
  • Water intrusion in the HO2S harness connector.
  • Low or high fuel system pressure.
  • Fuel that is contaminated.
  • Fuel saturation of the evaporative emission (EVAP) canister.
  • Exhaust leaks near the HO2S.
  • Engine vacuum leaks.
Did you find and correct the condition?
-
Go to Step 14
Go to Step 12
8
Test the signal circuit of the HO2S for a short to ground.
Did you find and correct the condition?
-
Go to Step 14
Go to Step 13
9
Test the signal circuit of the HO2S for a short to voltage.
Did you find and correct the condition?
-
Go to Step 14
Go to Step 13
10
Test the signal circuit of the HO2S for an open/high resistance.
Did you find and correct the condition?
-
Go to Step 14
Go to Step 13
11
Test the low reference circuit of the HO2S for a short to voltage, open, or high resistance.
Did you find and correct the condition?
-
Go to Step 14
Go to Step 13
12
Replace the HO2S.
Did you complete the replacement?
-
Go to Step 14
-
13
Replace the ECM.
Did you complete the replacement?
-
Go to Step 14
-
14
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running 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 15
15
Check if any additional DTCs are set.
Are any DTCs displayed that have not been diagnosed?
-
Go to applicable DTC table
System OK

Diagnostic Trouble Code (DTC) P0133

DTC Description

DTC P0133 : HO2S Slow Response Sensor 1

Circuit Description

The heated oxygen sensors (HO2S) are used for fuel control and post 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-to-fuel ratio. The control module supplies the HO2S with a reference, or bias voltage of approximately 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-to-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-to-fuel ratio sooner.

Conditions for Running the DTC

Conditions for Setting the DTC

or,

Action Taken When the DTC Sets

Refer to “Diagnostic Trouble Code (DTC) Type Definitions”

Conditions for Clearing the MIL/DTC

Refer to “Diagnostic Trouble Code (DTC) Type Definitions”

Diagnostic Aids

Normal scan tool voltage varies between 0.1volts and 0.9 volts while in closed loop.
Inspect the oxygen sensor wire. The oxygen sensor may be positioned incorrectly and contacting the exhaust manifold.
Check for an intermittent ground in the wire between the oxygen sensor and the engine control module.
Perform an injector balance test to determine if a restricted fuel injector may be causing the lean condition.
Vacuum of crankcase leaks will cause a lean running condition.
An exhaust manifold gasket leak of a cracked exhaust manifold may cause outside air to be pulled into the exhaust and past the sensor.

DTC P0133

Step Action Value(s) Yes No
1
Did you perform the Diagnostic System Check?
-
Go to Step 2
Go to "Diagnostic System Check"
2
Observe the DTC information with a scan tool.
Are there any other DTCs also set?
-
Go to applicable DTC table
Go to Step 3
3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running 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 4
Go to "Intermittent Conditions".
4
Test or inspect for the following conditions:
  • Lean or rich fuel injectors.
  • Water intrusion in the HO2S harness connector.
  • HO2S wiring harness damage.
  • Incorrect RTV sealant.
  • Low or high fuel system pressure.
  • Fuel that is contaminated.
  • Fuel saturation of the evaporative emission (EVAP) canister.
  • Exhaust leaks near the HO2S.
  • Engine vacuum leaks.
  • Engine oil consumption.
  • Engine coolant consumption.
Did you find and correct the condition?
-
Go to Step 6
Go to Step 5
5
Replace the HO2S.
Did you complete the replacement?
-
Go to Step 6
-
6
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running 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 7
7
Check if any additional DTCs are set.
Are any DTCs displayed that have not been diagnosed?
-
Go to applicable DTC table
System OK

Diagnostic Trouble Code (DTC) P0135, P0141

DTC Description

DTC P0135 : HO2S Heater Performance Sensor 1
DTC P0141 : HO2S Heater Performance Sensor 2

Circuit Description

The heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. A heating element inside the HO2S minimizes the time required for the sensor to reach operating temperature. Voltage is provided to the heater by the ignition 1 voltage circuit through a fuse. Ground is provided to the heater on the low control circuit by a low side driver within the control module. The control module monitors the current draw of the heater to determine if a failure is present.

Conditions for Running the DTC

Conditions for Setting the DTC

Action Taken When the DTC Sets

Refer to “Diagnostic Trouble Code (DTC) Type Definitions”

Conditions for Clearing the MIL/DTC

Refer to “Diagnostic Trouble Code (DTC) Type Definitions”

DTC P0135, P0141

Step Action Value(s) Yes No
1
Did you perform the Diagnostic System Check?
-
Go to Step 2
Go to "Diagnostic System Check"
2
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running 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 3
Go to "Intermittent Conditions".
3
  1. Turn OFF the ignition.
  2. Disconnect the wiring harness connector from the applicable HO2S.
  3. Turn the ignition switch ON.
  4. Connect a test lamp between the ignition 1 voltage supply circuit and ground.
Does the test lamp illuminate?
-
Go to Step 4
Go to Step 6
4
  1. Turn OFF the ignition.
  2. Connect the test lamp between the control circuit and B+.
Does the test lamp illuminate?
-
Go to Step 7
Go to Step 5
5
  1. Start the engine.
  2. Make sure the test lamp still connected.
Does the test lamp illuminate or flash?
-
Go to Step 10
Go to Step 8
6
Inspect the ignition 1 voltage supply circuit of the HO2S heater for short to ground, open/high resistance.
Did you find and correct the condition?
-
Go to Step 12
Go to Step 9
7
Inspect the control circuit of the HO2S heater for short to ground.
Did you find and correct the condition?
-
Go to Step 12
Go to Step 11
8
Inspect the control circuit of the HO2S heater for short to voltage, open/high resistance.
Did you find and correct the condition?
-
Go to Step 12
Go to Step 11
9
  1. Inspect the fuse that supplies voltage to the ignition 1 voltage supply circuit.
  2. If the fuse is open, test all the components connected to the ignition 1 voltage supply circuit.
Did you find and correct the condition?
-
Go to Step 12
Go to "Diagnostic System Check"
10
Replace the HO2S.
Did you complete the replacement?
-
Go to Step 12
-
11
Replace the ECM.
Did you complete the replacement?
-
Go to Step 12
-
12
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running 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 13
13
Check if any additional DTCs are set.
Are any DTCs displayed that have not been diagnosed?
-
Go to applicable DTC table
System OK

Diagnostic Trouble Code (DTC) P0171, P0172

DTC Description

DTC P0171 : Fuel Trim System Lean
DTC P0172 : Fuel Trim System Rich

Circuit Description

The engine control module (ECM) controls a Closed Loop air/fuel metering system in order to provide the best possible combination of driveability, fuel economy, and emission control. The ECM monitors the heated oxygen sensor (HO2S) signal voltage and adjusts the fuel delivery based on the signal voltage while in Closed Loop. A change made to the fuel delivery changes the long and short term fuel trim values. The short term fuel trim values change rapidly in response to the HO2S signal voltages. These changes fine tune the engine fueling. The long term fuel trim values change in response to trends in the short term fuel trim. The long term fuel trim makes coarse adjustments to fueling in order to re-center and restore control to short term fuel trim. The ideal fuel trim values are around 0 percent. A positive fuel trim value indicates that the ECM is adding fuel in order to compensate for a lean condition. A negative fuel trim value indicates that the ECM is reducing the amount of fuel in order to compensate for a rich condition. The fuel trim cells are based on the engine speed and load.

Conditions for Running the DTC

Conditions for Setting the DTC

(P0171)
(P0172)

Action Taken When the DTC Sets

Refer to “Diagnostic Trouble Code (DTC) Type Definitions”

Conditions for Clearing the MIL/DTC

Refer to “Diagnostic Trouble Code (DTC) Type Definitions”

Diagnostic Aids

DTC P0171, P0172

Step Action Value(s) Yes No
1
Did you perform the Diagnostic System Check?
-
Go to Step 2
Go to "Diagnostic System Check"
2
Observe the DTC information with a scan tool.
Are there any other DTCs also set?
-
Go to applicable DTC table
Go to Step 3
3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running 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 4
Go to "Intermittent Conditions".
4
  1. Turn the ignition ON, without engine running.
  2. Observe the MAP sensor reading on the scan tool to the barometric pressure table.
Is the MAP sensor pressure is within the range specified for your altitude?
-
Go to Step 5
Go to DTC P0107, P0108 table
5
  1. Start the engine.
  2. Observe the TP sensor percentage parameter on the scan tool.
Is the TP sensor parameter less than 10%?
-
Go to Step 6
Go to P0122, P0123, P0222, P0223, P2135 table
6
  1. Engine is running.
  2. Observe the HO2S voltage parameter on the scan tool.
Does the reading fluctuate within 200 ~ 800 mV?
-
Go to Step 7
Go to DTC P0131, P0132, P0134, P0137, P0138, P0140 table
7
Inspect for the following conditions:
  • Fuel contamination.
  • Splits, kinks, or improper connections at the vacuum hoses.
  • The fuel system is operating lean or rich.
  • The fuel injectors are operating lean or rich.
  • Missing, restricted, or leaking exhaust components.
  • Vacuum leaks at the intake manifold, throttle body, and injector O-rings (P0171).
  • Leaking crankcase ventilation system (P0171).
  • The air intake duct for being collapsed or restricted possibly by a restricted air filter (P0172).
  • Excessive fuel in crankcase (P0172).
  • Incorrect operation of the evaporative emission (EVAP) control system (P0172).
Did you find and correct the condition?
-
Go to Step 8
Refer to symptoms on Section 1C2, “Diagnosis”
8
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running 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 9
9
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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