Engine

P0229 — Throttle/Pedal Position Sensor “C” Circuit Intermittent

Severity: medium Drive with care, to a shop

What P0229 means

The engine control module constantly reads several throttle or accelerator pedal position signals to work out how much air and fuel the engine needs. P0229 means the signal from circuit “C” drops out, jumps around or goes out of range from time to time. Because the fault comes and goes, it may not show up on every drive.

Symptoms

  • Check engine light on
  • Erratic or delayed response to the gas pedal
  • Intermittent loss of power or limp mode
  • Unstable idle
  • Possible stalling at low speeds or when stopping

Possible causes

  1. Poor contact or corrosion in the throttle or pedal sensor connector
  2. Damaged, chafed or broken wiring in the sensor “C” circuit
  3. Worn or failing throttle position sensor or accelerator pedal position sensor
  4. Open circuit or short to ground or power in the signal wire
  5. Dirty or worn electronic throttle body
  6. Internal ECM input circuit fault (rare)

How to diagnose

  1. Read all codes and freeze frame data, and look for other throttle or pedal codes
  2. Inspect the throttle and pedal connectors for corrosion, loose terminals and moisture
  3. Wiggle the harness and connector with the engine running while watching the signal on a scan tool
  4. Compare all sensor circuits live while pressing the pedal slowly and look for dropouts or spikes
  5. Use a multimeter to check the 5 V supply, ground and signal wire for opens and shorts
  6. Check wire resistance from the sensor to the ECM
  7. Inspect the throttle body for dirt or sticking
  8. If the wiring is good, swap in a known good sensor before suspecting the ECM

Common fixes

  • Clean the connectors, restore terminal tension and protect them with dielectric grease
  • Repair or replace the damaged section of wiring harness
  • Replace the accelerator pedal assembly or the throttle body
  • Reprogram or replace the ECM if an internal fault is confirmed
  • Clear codes and perform a throttle relearn after the repair if the vehicle requires it

Questions and answers

Can I drive with a P0229 code?

Only carefully and a short distance to a shop. The fault is intermittent, so power can drop without warning and the engine may stall.

Why does P0229 come and go?

The code describes an intermittent fault, most often a poor connection or a damaged wire. The signal drops out with vibration, moisture or temperature changes and then returns to normal.

Should I replace the pedal or throttle body right away?

No. Check the connectors and wiring first, since they are the most common cause. Replace the sensor only when the wiring is good and the signal is still unstable.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.