P0135

P0135-O2 SENSOR 1/1 HEATER PERFORMANCE

Special Tools:










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

Theory of Operation

The engine after treatment system monitors the oxygen content in the diesel engine exhaust. The Powertrain Control Module (PCM) 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 PCM will set the fault if it receives an FMI (Failure Mode Indicator) message from the Smart O2 Module. The PCM will illuminate the MIL lamp immediately when the diagnostic runs and fails. The PCM will turn off the MIL lamp diagnostic runs and passes in four consecutive drive cycles.

- When Monitored:
This diagnostic runs when the engine is running.

- Set Condition:
The Powertrain Control Module (PCM) will set the fault if it receives an 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 O2 Sensor or O2 Sensor Module, check after treatment wiring harness for spread terminals. For wiring harness checking procedure, DO NOT back probe, use Electric Terminal Tool Kit.

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 75 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. CHECK THE (K99) O2 1/1 HEATER SUPPLY CIRCUIT FOR AN OPEN/HIGH RESISTANCE




1. Disconnect the Oxygen Sensor 1/1 harness connector.
2. Disconnect the Smart O2 Sensor Module harness connector.

NOTE: Check connectors - Clean/repair as necessary, inspect for signs of Water intrusion in the connector.

3. Measure the resistance of the (K99) O2 Sensor 1/1 Heater Supply circuit between the O2 Sensor 1/1 harness connector and the Smart O2 Sensor Module harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 3

No

- Repair the (K99) O2 Sensor 1/1 Heater Supply circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

3. CHECK THE (K79) O2 1/1 HEATER RETURN CIRCUIT FOR AN OPEN/HIGH RESISTANCE




1. Measure the resistance of the (K79) O2 Sensor 1/1 Heater Return circuit between the O2 Sensor 1/1 harness connector and the Smart O2 Sensor Module harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 4

No

- Repair the (K79) O2 Sensor 1/1 Heater Return circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

4. CHECK THE OXYGEN SENSOR




1. Measure resistance of the O2 Sensor Heater between the (K99) O2 Sensor 1/1 Heater Supply and (K79) O2 Sensor 1/1 Heater Return circuit at the O2 Sensor.

Is the resistance 3.2 +/- 0.8 Ohms at ambient temperature?

Yes

- Replace Smart O2 Sensor Module.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Replace the O2 Sensor.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.