P0120 OBD II Trouble Code Throttle Position Sensor/Switch (TPS) A Circuit Malfunction

Detailed information on troubleshooting and repairing a p0120 vehicle trouble code which refers to a malfunction in the throttle position sensor/switch TPS A circuit. Also includes links to relevant forum topics on the code.

Symptoms of P0120 OBD II Trouble Code

  • MIL (Malfunction Indicator Lamp) illumination
  • Misfiring at idle or at highway speed
  • Poor idle quality
  • Possibly won't idle
  • Possibly starts and stalls

Common Causes of P0120 OBD II Trouble Code

  • Sticking throttle return spring
  • MAP or TPS connector corrosion
  • Misrouted harness causing chafing
  • Bad TPS
  • Bad PCM