P0135

P0135-O2 SENSOR 1/1 HEATER PERFORMANCE

Special Tools:










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

Theory of Operation

This diagnostic provides a continuous check of the O2 heater circuit during operation. The heater circuit is momentarily disabled to allow a resistance measurement to be taken to infer heater temperature. The current delivery to the heater is duty cycled to maintain a specific target temperature. The error from the target temperature is continuously monitored to assess heater performance.

- When Monitored:
Continuously during O2 sensor heater operation with battery voltage between 10.4 and 15.75 Volts and no O2 sensor circuit DTCs present.

- Set Condition:
The Powertrain Control Module (PCM) detects no temperature change in the O2 sensor heater element 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.

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 Heater Test.
4. With the scan tool, monitor 1/1 O2 Sensor 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 O2 Heater Element across the 1/1 O2 Sensor connector between the O2 Heater Control terminal and the Heater ground terminal.

NOTE: 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

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

3. (K99) O2 1/1 HEATER CONTROL CIRCUIT OPEN




1. Disconnect the C2 PCM harness connector.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the PCM Pinout Box (8815A) to perform diagnosis.

2. Measure the resistance of the (K99) O2 1/1 Heater Control circuit from the O2 harness connector to the appropriate terminal of PCM Pinout Box.

Is the resistance below 0.5 of an ohm?

Yes

- Go To 4

No

- Repair the excessive resistance in the (K99) O2 1/1 Heater Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

4. (Z908) O2 1/1 HEATER GROUND CIRCUIT OPEN




1. Using a 12-volt test light connected to 12 Volts, check the (Z908) Ground circuit in the 1/1 Oxygen Sensor harness connector.

NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.

Is the test light illuminated and bright?

Yes

- Go To 5

No

- Repair the excessive resistance in the (Z908) O2 1/1 Heater ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

5. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Oxygen 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 Sensor and Control Module connectors.
4. Search for 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.