P0135

P0135-O2 SENSOR 1/1 HEATER PERFORMANCE

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





Theory of Operation

For the Wideband 02 Sensor to deliver accurate readings the sensing elements must be heated. A Positive Temperature Coefficient (PTC) element inside the O2 Sensor heats up as current passes through it. This allows the system to enter Closed Loop quickly. The Powertrain Control Module (PCM) turns on this circuit based on Engine Coolant Temperature (ECT) and engine loads. The PCM monitors the O2 Sensor's heater for proper operation. If a malfunction occurs the circuit is turned off and a DTC will set.

- When Monitored:
Engine running, exhaust temperature above 200°C (392°F). Battery voltage between 11.0 volts and 16.0 volts.

- Set Condition:
The Powertrain Control Module (PCM) detects that the O2 Sensor Heater element temperature is below 600°C (1112°F) for 9.0 seconds or above 922°C (1692°F) for 20.0 seconds when the heater circuit is active. The heater temperature is obtained by measuring the heater resistance and calculating the heater temperature. Two trip fault. Three good trips to turn off the MIL.





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

Diagnostic Test

1. O2 SENSOR HEATER OPERATION
1. Turn the ignition off.

NOTE: Wait a minimum of eight minutes to allow the O2 Sensor to cool down before continuing the test. Allow the O2 Sensor voltage to stabilize between 4.6 and 5.0 Volts.

2. Ignition on, engine not running.
3. With the scan tool, actuate the O2 Sensor 1/1 Heater Test.
4. Using the scan tool, monitor O2 Sensor 1/1 voltage for at least two minutes.

Does the voltage stay above 4.5 volts?

Yes

- Go To 2

No

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

2. O2 SENSOR HEATER ELEMENT
1. Turn the ignition off.

NOTE: Allow the O2 sensor to cool down to room temperature.

2. Disconnect the O2 Sensor harness connector.
3. Measure the resistance of the Heater Element through the O2 Sensor. Measure at the (F344) Fused ASD Relay Output terminal and the (K79) O2 Sensor Heater Control terminal of the O2 Sensor 1/1 connector.

NOTE: The O2 Heater Element resistance values should be measured at 21.1°C (70 F). The resistance value will vary with different temperature values.

Is the resistance of the O2 Sensor Heater Element between 2.0 and 30.0 Ohms?

Yes

- Go To 3

No

- Verify that there is good pin to terminal contact in the O2 Sensor and Powertrain Control Module connectors. If OK, replace the O2 Sensor. .
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

3. (K79) O2 SENSOR 1/1 HEATER CONTROL CIRCUIT OPEN/HIGH RESISTANCE
1. Disconnect the PCM C1 harness connector.
2. Measure the resistance of the (K79) O2 Sensor 1/1 Heater Control circuit between the O2 Sensor harness connector and the of PCM C1 harness connector.

Is the resistance below 0.5 Ohms?

Yes

- Go To

No

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

4. (F344) FUSED ASD RELAY OUTPUT CIRCUIT OPEN/HIGH RESISTANCE
1. Remove the ASD Relay from the PDC.
2. Measure the resistance of the (F344) Fused ASD Relay Output circuit between the O2 Sensor harness connector and the ASD Relay Output terminal in the PDC.

Is the resistance below 0.5 Ohms?

Yes

- Go To 5

No

- Repair the excessive resistance in the ASD Relay O2 1/1 Heater Feed circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

5. (K41) O2 SENSOR 1/1 SIGNAL CIRCUIT OPEN/HIGH RESISTANCE
1. Disconnect the PCM C1 harness connector.
2. Measure the resistance of the (K41) O2 Sensor 1/1 Signal circuit between the O2 Sensor harness connector and the of PCM C1 harness connector.

Is the resistance below 0.5 Ohms?

Yes

- Go To 6

No

- Repair the (K41) O2 Sensor 1/1 Signal circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

6. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the O2 Sensor 1/1 and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the O2 Sensor1/1 and Powertrain Control Module connectors.
4. Perform any Technical Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module. .
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.