P0143 OBD II Trouble Code 02 Sensor Circuit Low Voltage (Bank I Sensor 3)

Detailed information on troubleshooting and repairing a p0143 DTC code which refers to the O2 sensor circuit with low voltage. Also includes links to relevant forum topics on the code.

Symptoms of P0143 OBD II Trouble Code

  • MIL (Malfunction Indicator Lamp) illumination
  • Engine performance issues
  • Engine running rough
  • Engine running rich
  • Poor idle

Common Causes of P0143 OBD II Trouble Code

  • Air leaks in exhaust in front of o2 sensor giving false reading
  • O2 sensor connector damaged
  • O2 sensor signal circuit is shorted to ground
  • O2 sensor ground circuit is open
  • O2 sensor has failed (it may be contaminated with fuel or coolant)
  • PCM has failed