Symptoms of P0051 OBD II Trouble Code
- A short in the heater circuit in the sensor
- A failed O2 sensor heater
- Wiring/connectors broken/frayed leading to sensor and/or relay
- Failed PCM/ECM
Common Causes of P0051 OBD II Trouble Code
- check for 12 volts at the heater circuit feed (hint: unplug the sensor and
check at the wiring connector to do this measurement) - check the ground circuit for continuity
- measure the resistance of the heater circuit (done on the sensor itself)
- measure the resistance and voltage of the wiring