P0135

P0135-O2 SENSOR 1/1 HEATER PERFORMANCE





For a complete wiring diagram Refer to Diagrams/Electrical.

Theory of Operation


The engine aftertreatment system monitors the O2 content in the diesel engine exhaust. The 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 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:
This diagnostic runs when the engine is running.

- Set Condition:
The 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. Initial Inspection and Diagnostic Overview


Diagnostic Test


1. (K99) 02 1/1 HEATER SUPPLY CIRCUIT OPEN




Disconnect the Oxygen sensor and the Smart O2 Sensor Module from the Aftertreatment Wiring Harness.

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

Measure the resistance of the (K99) 02 1/1 heater supply circuit between the O2 sensor harness connector and the Smart O2 sensor module harness connector.
Is the resistance less than 10 Ohms?

Yes


- Go To 2


No


- Replace Aftertreatment Wiring Harness.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



2. (K79) 02 1/1 HEATER RETURN CIRCUIT OPEN




Measure the resistance of the (K79) 02 1/1 heater return circuit between the O2 sensor harness connector and the Smart O2 sensor module harness connector.
Is the resistance less than 10 Ohms?

Yes


- Go To 3


No


- Replace Aftertreatment Wiring Harness.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



3. (K89) 02 1/1 PUMP CURRENT CIRCUIT OPEN




Measure the resistance of the (K89) 02 1/1 pump current circuit between the O2 sensor harness connector and the Smart O2 sensor module harness connector.
Is the resistance less than 10 Ohms?

Yes


- Go To 4


No


- Replace Aftertreatment Wiring Harness.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



4. (K902) 02 1/1 RETURN CIRCUIT OPEN




Measure the resistance of the (K902) 02 1/1 return circuit between the O2 sensor harness connector and the Smart O2 sensor module harness connector.
Is the resistance less than 10 Ohms?

Yes


- Go To 5


No


- Replace Aftertreatment Wiring Harness.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



5. (K103) 02 1/1 PUMP CELL CURRENT TRIM CIRCUIT OPEN




Measure the resistance of the (K103) 02 1/1 pump cell current trim circuit between the O2 sensor harness connector and the Smart O2 sensor module harness connector.
Is the resistance less than 10 Ohms?

Yes


- Go To 6


No


- Replace Aftertreatment Wiring Harness.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



6. (K41) 02 1/1 SIGNAL CIRCUIT OPEN




Measure the resistance of the (K41) 02 1/1signal circuit between the O2 sensor harness connector and the Smart O2 sensor module harness connector.
Is the resistance less than 10 Ohms?

Yes


- Go To 7


No


- Replace Aftertreatment Wiring Harness.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



7. OXYGEN SENSOR




Measure resistance of the 02 sensor heater between the (K99) 02 heater supply and (K79) 02 heater return circuits.
Is the resistance 3.2 +/- 0.8 ohms at ambient temperature?

Yes


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


No


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