P0135
P0135-O2 SENSOR 1/1 HEATER PERFORMANCE
Theory of Operation
The Powertrain Control Module (PCM) performs a continuous check of the O2 sensor 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:
With the engine running, O2 sensor heater duty cycle greater than 0%, and battery voltage greater than 11.0 volts.
- Set Condition:
The PCM detects no O2 sensor output when the heater is powered up. 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. OXYGEN SENSOR 1/1 HEATER CONTROL OPERATION
1. Turn the ignition off.
NOTE: Wait a minimum of eighty minutes to allow the sensor to cool down before continuing. The sensor voltage should stabilize between 2.47 and 2.52 volts.
2. Turn the ignition on.
3. With a scan tool, actuate the Oxygen Sensor 1/1 heater control.
4. With the scan tool, monitor 1/1 O2 Sensor Volts for at least two minutes.
Does the voltage stay between 2.47 and 2.52 volts?
Yes
- Go To 2
No
- Perform the CHECKING FOR AN INTERMITTENT DTC diagnostic procedure. Checking for an Intermittent DTC.
2. OXYGEN SENSOR 1/1
1. Turn the ignition off.
NOTE: Wait a minimum of eight minutes to allow the sensor to cool down before continuing.
2. Disconnect the Oxygen Sensor 1/1 harness connector.
3. Measure the resistance of the O2 sensor heater element across the Oxygen Sensor 1/1 connector between the heater control terminal and the ground terminal.
NOTE: The O2 heater element resistance should be measured at 70° F (21.1° C). The resistance value will vary at different temperatures.
Is the resistance between 2.0 and 30.0 Ohms?
Yes
- Go To 3
No
- Replace the Oxygen Sensor 1/1.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
3. (K99) O2 1/1 HEATER CONTROL CIRCUIT OPEN OR HIGH RESISTANCE
1. Disconnect the Powertrain Control Module (PCM) harness connector.
NOTE: When checking circuits at the Powertrain Control Module (PCM), be careful not to damage or distort the connector terminals. Improper measurement technique could result in poor pin to terminal contact.
2. Measure the resistance of the (K99) O2 1/1 Heater Control circuit from the Oxygen Sensor 1/1 harness connector to the Powertrain Control Module (PCM) harness connector.
Is the resistance below 0.5 of an Ohm?
Yes
- Go To 4
No
- Repair the (K99) O2 1/1 Heater Control circuit for an open circuit or high resistance.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
4. (Z931) GROUND CIRCUIT OPEN OR HIGH RESISTANCE
1. Using a 12-volt test light connected to 12 volts, check the (Z931) Ground circuit in the Oxygen Sensor 1/1 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 (Z931) Ground circuit for an open circuit or high resistance.
- Perform the PCM VERIFICATION TEST. PCM 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.
4. Perform any Technical Service Bulletins that may apply.
Were any problems found?
Yes
- Repair as necessary.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Replace and program the Powertrain Control Module (PCM).
- Perform the PCM VERIFICATION TEST. PCM Verification Test.