P0135 - O2 Sensor 1/1 Heater Performance: Notes
Theory of Operation
This diagnostic provides 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 calculate 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 determine heater performance.
- >>When Monitored:<< Engine running and heater duty cycle greater than 0%. Battery voltage greater than 11.0 Volts.
- >>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.
| Possible Causes |
|---|
| (K99) O2 SENSOR 1/1 HEATER CONTROL CIRCUIT OPEN |
| (Z902) O2 SENSOR 1/1 HEATER GROUND CIRCUIT OPEN |
| O2 SENSOR 1/1 |
| POWERTRAIN CONTROL MODULE (PCM) |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to Pre-Diagnostic Troubleshooting Procedure .