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P0131






P0131-O2 SENSOR 1/1 CIRCUIT LOW





For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams. Electrical Diagrams

Theory of Operation

The engine aftertreatment system monitors the O2 content in the diesel engine exhaust. The Engine Control Module (ECM) monitors the exhaust gases for oxygen content and varies the rich/lean fuel mixture of the intake air fuel mixture to adjust the system. This diagnostic monitors the status message broadcast by the Smart O2 Sensor Module for the Upstream O2 Sensor circuit. The ECM will set the fault if it receives a FMI (Failure Mode Indicator) message from the Smart O2 Sensor Module. The ECM will illuminate the MIL lamp immediately when the diagnostic runs and fails. The ECM will turn off the MIL lamp diagnostic runs and passes in four consecutive drive cycles.

- When Monitored:
When the engine is running.

- Set Condition:
The Engine Control Module (ECM) will set the fault if it receives a FMI (Failure Mode Indicator) message from the Smart O2 Module.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

NOTE: Before replacing any O2 Sensor or O2 Sensor Module, check aftertreatment wiring harness for spread terminals. For wiring harness checking procedure, DO NOT back probe, use Miller Tool Kit 8197A (6801 Tool).

1. ACTIVE DTC
1. Turn the ignition on.
2. With the scan tool, record all Freeze frame data.
3. With the scan tool, erase DTCs.
4. Turn the ignition off for 30 seconds.
5. Start the engine and let idle for up to five minutes.
6. With the scan tool, read DTCs.

Did the DTC reset?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

2. O2 SENSOR 1/1 CIRCUITS SHORTED TO VOLTAGE




1. Turn the ignition off.
2. Disconnect the O2 Sensor Module harness connector.
3. Turn the ignition on.
4. Measure the voltage on the (K41) O2 Sensor 1/1 Signal circuit at the Smart O2 Sensor Module harness connector.
5. Measure the voltage on the (K103) O2 Sensor 1/1 Pump Cell Current Trim circuit at the Smart O2 Sensor Module harness connector.
6. Measure the voltage on the (K902) O2 Sensor 1/1 Return circuit at the Smart O2 Sensor Module harness connector.

Is there voltage present on any circuit?

Yes

- Repair the short to voltage in the circuit where voltage was present.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 3

3. O2 SENSOR 1/1 CIRCUITS SHORTED TO GROUND




1. Turn the ignition off.
2. Disconnect the O2 Sensor 1/1 harness connector.
3. Measure the resistance between ground and the (K41) O2 Sensor 1/1 Signal circuit at the Smart O2 Sensor Module harness connector.
4. Measure the resistance between ground and the (K103) O2 Sensor 1/1 Pump Cell Current Trim circuit at the Smart O2 Sensor Module harness connector.
5. Measure the resistance between ground and the (K902) O2 Sensor 1/1 Return circuit at the Smart O2 Sensor Module harness connector.

Is the resistance below 10k Ohms on any circuit?

Yes

- Repair the short to ground in the appropriate circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 4

4. (K41) O2 1/1 SIGNAL CIRCUIT OPEN




1. Measure the resistance of the (K41) O2 1/1 Signal circuit between the O2 Sensor harness connector and the Smart O2 Sensor Module harness connector.

Is the resistance below 10.0 Ohms?

Yes

- Go To 5

No

- Repair the open or high resistance in the (K41) O2 1/1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

5. (K103) O2 1/1 PUMP CELL CURRENT TRIM CIRCUIT OPEN




1. Measure the resistance of the (K103) O2 1/1 Pump Cell Current Trim circuit between the O2 Sensor harness connector and the Smart O2 Sensor Module harness connector.

Is the resistance below 10.0 Ohms?

Yes

- Go To 6

No

- Repair the open or high resistance in the (K103) O2 1/1 Pump Cell Current Trim circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

6. (K902) O2 1/1 RETURN CIRCUIT OPEN




1. Measure the resistance of the (K902) O2 1/1 Return circuit between the O2 Sensor harness connector and the Smart O2 Sensor Module harness connector.

Is the resistance below 10.0 Ohms?

Yes

- Go To 7

No

- Repair the open or high resistance in the (K902) O2 1/1 Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

7. OXYGEN SENSOR SOOTED
1. Remove the O2 Sensor 1/1.
2. Carefully clean the soot from the O2 Sensor.

NOTE: Do not tap or bang sensor to remove loose debris. This will damage the sensor.

3. Reinstall the O2 Sensor 1/1.
4. With the scan tool, erase DTCs.
5. Turn the ignition off for 30 seconds.
6. Start the engine and let idle for two minutes.
7. With the scan tool, read DTCs.

Did the DTC reset?

Yes

- Go To 8

No

- Repair complete.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

8. OXYGEN SENSOR AND O2 SENSOR CONTROL MODULE
1. Remove the O2 Sensor 1/1 and O2 Sensor 1/2.
2. Install the O2 Sensor 1/1 in the O2 Sensor 1/2 position.
3. Install the O2 Sensor 1/2 in the O2 Sensor 1/1 position.
4. With the scan tool, erase DTCs.
5. Turn the ignition off for 30 seconds.
6. Start the engine and let idle for two minutes.
7. With the scan tool, read DTCs.

Did the DTC change to P0137?

Yes

- Reinstall the O2 Sensor 1/2 back to it's original position and replace the O2 Sensor 1/1.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Replace the O2 Sensor Control Module. Return the O2 Sensors back to their original positions.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

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