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Diagnostic Trouble Code (DTC) P2177, P2178, P2187, P2188, P2191, P2192

DTC Description

DTC P2177 : Fuel Trim System Lean at Cruise or Accel
DTC P2178 : Fuel Trim System Rich at Cruise or Accel
DTC P2187 : Fuel Trim System Lean at Idle
DTC P2188 : Fuel Trim System Rich at Idle
DTC P2191 : Fuel Trim System Lean at Higher Load
DTC P2192 : Fuel Trim System Rich at Higher Load

Circuit Description

The engine control module (ECM) controls a Closed Loop air/fuel metering system in order to provide the best possible combination of drivability, 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

(Common)
(P2177, P2178)
(P2187, P2188)
(P2191, P2192)

Conditions for Setting the DTC

(P2177)
(P2178)
(P2187, P2191)
(P2188, P2192)

Action Taken When the DTC Sets

Conditions for Clearing the MIL/DTC

Diagnostic Aids

DTC P2177, P2178, P2187, P2188, P2191, P2192

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 “Intermittents”
4
  1. Turn the ignition ON, without engine running.
  2. Compare the MAP sensor reading on the scan tool to the value of the normal vehicle.
Is the MAP sensor pressure is near the value of the normal vehicle?
-
Go to Step 5
Go to 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 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 (P2177, P2187, or P2191).
  • Leaking crankcase ventilation system (P2177, P2187, or P2191).
  • The air intake duct for being collapsed or restricted possibly by a restricted air filter (P2178, P2188, or P2192).
  • Excessive fuel in crankcase (P2178, P2188, or P2192).
  • Incorrect operation of the evaporative emission (EVAP) control system (P2178, P2188, or P2192).
Did you find and correct the condition?
-
Go to Step 8
Go to symptoms on Section 1C1, “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 there any DTCs that have not been diagnosed?
-
Go to applicable DTC table
System OK

Diagnostic Trouble Code (DTC) P2231

HO2S Signal Circuit Shorted to Heater Circuit Sensor 1

Circuit Description

The Engine control relay applies positive voltage to the heater ignition voltage circuits of the O2 sensor. The ECM applies a pulse width modulated (PWM) ground to the heater control circuit of the O2 sensor through a device within the ECM called a Driver, to control the O2 sensor rate of heating. An O2 sensor signal circuit shorted to heater control circuit DTC sets if the ECM detects the O2 sensor signal voltage is increasing or decreasing at the same rate as the O2 sensor heater control circuit.

Conditions for Running the DTC

Conditions for Setting the DTC

or

Action Taken When the DTC Sets

Conditions for Clearing the MIL/DTC

DTC P2231 - HO2S Signal Circuit Shorted to Heater Circuit Sensor 1

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. Disconnect the engine oil pressure switch.
  2. Start the engine.
  3. Allow the engine to reach the normal operating temperature.
  4. Using the Scan Tool, select DTC display function.
Did the DTC 2231 fail this ignition?
-
Go to Step 3
-
3
  1. Disconnect the appropriate O2 sensor connector.
  2. From the O2 sensor to the sensor wiring connector, test the following circuit for a shorted to the sensor heater control circuit fault condition:
    • Reference signal circuit,
    • low reference circuit,
    • pump current,
    • input pump current.
Did you find fault?
-
Go to Step 5
Go to Step 4
4
  1. Disconnect the ECM and the appropriate O2 sensor connector.
  2. From the O2 sensor wiring connector to the ECM wiring connector, test the following circuit for a shorted to the sensor heater control circuit fault condition:
    • Reference signal circuit,
    • low reference circuit,
    • pump current,
    • input pump current.
Did you find and correct the condition?
-
Go to Step 7
Go to Step 6
5
Replace the appropriate O2 sensor.
Did you complete the replacement?
-
Go to Step 7
-
6
Replace the ECM.
Did you complete the replacement?
-
Go to Step 7
-
7
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. 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) P2232

HO2S Signal Circuit Shorted to Heater Circuit Sensor 2

Circuit Description

The Engine control relay applies positive voltage to the heater ignition voltage circuits of the O2 sensor. The ECM applies a pulse width modulated (PWM) ground to the heater control circuit of the O2 sensor through a device within the ECM called a Driver, to control the O2 sensor rate of heating. An O2 sensor signal circuit shorted to heater control circuit DTC sets if the ECM detects the O2 sensor signal voltage is increasing or decreasing at the same rate as the O2 sensor heater control circuit.

Conditions for Running the DTC

Conditions for Setting the DTC

or

Action Taken When the DTC Sets

Conditions for Clearing the MIL/DTC

DTC P2232 - HO2S Signal Circuit Shorted to Heater Circuit Sensor 2

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. Disconnect the engine oil pressure switch.
  2. Start the engine.
  3. Allow the engine to reach the normal operating temperature.
  4. Using the Scan Tool, select DTC display function.
Did the DTC 2232 fail this ignition?
-
Go to Step 3
-
3
  1. Disconnect the appropriate O2 sensor connector.
  2. From the O2 sensor to the sensor wiring connector, test the following circuit for a shorted to the sensor heater control circuit fault condition:
    • Reference signal circuit,
    • low reference circuit,
    • pump current,
    • input pump current.
Did you find fault?
-
Go to Step 5
Go to Step 4
4
  1. Disconnect the ECM and the appropriate O2 sensor connector.
  2. From the O2 sensor wiring connector to the ECM wiring connector, test the following circuit for a shorted to the sensor heater control circuit fault condition:
    • Reference signal circuit,
    • low reference circuit,
    • pump current,
    • input pump current.
Did you find and correct the condition?
-
Go to Step 7
Go to Step 6
5
Replace the appropriate O2 sensor.
Did you complete the replacement?
-
Go to Step 7
-
6
Replace the ECM.
Did you complete the replacement?
-
Go to Step 7
-
7
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. 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) P2270

HO2S Signal Stuck Lean Sensor 2

Circuit Description

The Engine control relay applies positive voltage to the heater ignition voltage circuits of the O2 sensor. The ECM applies a pulse width modulated (PWM) ground to the heater control circuit of the O2 sensor through a device within the ECM called a Driver, to control the O2 sensor rate of heating. The ECM applies a voltage of approximately 450 mV between the reference signal circuit and low reference circuit of the O2 sensor while the sensor temperature is less than the operating range. Once the O2 sensor reaches operating temperature, the sensor varies this reference signal voltage, which constantly fluctuates between the high voltage output and the low voltage output. The ECM monitors, stores and evaluates the O2 sensor voltage fluctuation information to determine the level of oxygen concentration in the exhaust.

Conditions for Running the DTC

Conditions for Setting the DTC

Action Taken When the DTC Sets

Conditions for Clearing the MIL/DTC

DTC P2270 - HO2S Signal Stuck Lean Sensor 2

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. Disconnect the engine oil pressure switch.
  2. Start the engine.
  3. Allow the engine to reach the normal operating temperature.
  4. Using the Scan Tool, select DTC display function.
Did the DTC 2270 fail this ignition?
-
Go to Step 3
-
3
Are DTCs relating to the heater circuit of the O2 sensor also set?
-
-
Go to Step 4
4
  1. Disconnect the appropriate O2 sensor wiring connector.
  2. Switch on the ignition with the engine not running.
  3. Using a digital multimeter, measure the voltage between the O2 sensor reference signal circuit and low reference circuit.
Does the multimeter display specified value?
-
Go to Step 7
Go to Step 5
5
Test the reference signal circuit of the O2 sensor for a high resistance, open circuit, short to ground or short to voltage fault condition.
Did you find and correct the condition?
-
Go to Step 10
Go to Step 6
6
Test the low reference circuit of the O2 sensor for a high resistance, open circuit, short to ground or short to voltage fault condition.
Did you find and correct the condition?
-
Go to Step 10
Go to Step 9
7
Test or inspect for the following conditions that may cause the O2 sensor to detect an incorrect air/fuel mixture:
  • lean or rich fuel injector fuel delivery,
  • restricted air intake system,
  • contaminated fuel,
  • low fuel line pressure,
  • exhaust leak near the O2 sensor, and
  • leak in the crankcase or vacuum line.
Did you find and correct the condition?
-
Go to Step 10
Go to Step 8
8
Replace the appropriate O2 sensor.
Did you complete the replacement?
-
Go to Step 10
-
9
Replace the ECM.
Did you complete the replacement?
-
Go to Step 10
-
10
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. 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 2
11
Check if any additional DTCs are set.
Are there any DTCs that have not been diagnosed?
-
Go to applicable DTC table
System OK


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