P0051 OBD II Trouble Code Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 2 Sensor 1) - DTC Code

Detailed information on troubleshooting and repairing a p0051 automotive trouble code which refers to an oxygen sensor heater circuit that is low. Also includes links to relevant forum topics on the code.

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