Loose, corroded or damaged connector at the throttle body or accelerator pedal sensor; Chafed, broken or intermittently open/short-circuited wiring in the sensor signal, reference or earth circuits; Worn track or failing internal electronics in the throttle position or pedal position sensor; Dirty or faulty throttle body or throttle motor causing erratic position feedback; Unstable sensor supply voltage or poor earth, including low battery voltage or a poor engine earth strap; Water ingress or contamination in the connector or sensor housing; Fault within the engine control unit itself or an outdated calibration, where the manufacturer has documented this for the model.

P0229

Throttle/Pedal Position Sensor/Switch C Circuit Intermittent.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
2: AreaFuel and air metering (injector circuit)
29: FaultThe specific fault in that area

What it means

P0229 is the generic SAE J2012 code for an intermittent fault in the Throttle/Pedal Position Sensor/Switch C circuit. The engine control unit has seen the signal from that sensor drop out, spike or jump to an implausible value for short periods, rather than staying faulty continuously. Which physical sensor is 'C' (throttle body sensor or accelerator pedal sensor) depends on the make, model and engine, so check the manufacturer's wiring information.

Symptoms

Engine warning light on
Intermittent loss of power or limp mode with reduced throttle response
Hesitation or surging when pressing or lifting the accelerator
Unstable or erratic idle
Occasional stalling or difficulty starting
Cruise control not working

Possible causes

Loose, corroded or damaged connector at the throttle body or accelerator pedal sensorlikely
Chafed, broken or intermittently open/short-circuited wiring in the sensor signal, reference or earth circuitslikely
Worn track or failing internal electronics in the throttle position or pedal position sensorlikely
Dirty or faulty throttle body or throttle motor causing erratic position feedbackpossible
Unstable sensor supply voltage or poor earth, including low battery voltage or a poor engine earth strappossible
Water ingress or contamination in the connector or sensor housingpossible
Fault within the engine control unit itself or an outdated calibration, where the manufacturer has documented this for the modelrare

How to diagnose

Read and record all stored and pending codes and the freeze frame data, noting engine speed, load and conditions when the fault set.
Check for related codes for other throttle or pedal sensors, as this helps identify which sensor is 'C' on this vehicle.
Inspect the throttle body and pedal sensor connectors and wiring for damage, corrosion, bent or pushed-back pins, moisture and rubbing points.
With the engine running, view live data for the throttle and pedal position signals and wiggle the connectors and harness to see if the readings drop out or jump.
Sweep the pedal slowly through its full travel and watch for smooth, matching readings on all pedal sensor tracks, looking for glitches or flat spots.
Check the sensor supply voltage, signal and earth circuits against the manufacturer's specification, including a voltage drop test on the earth.
Check battery condition and charging voltage, and the main engine earth connections.
Inspect the throttle body for carbon build-up and check smooth movement, following the manufacturer's procedure for the model.

How to fix

Clean, repair or replace faulty connectors and terminals, and treat any corrosion or moisture ingress.
Repair or replace damaged wiring sections, securing the harness away from sharp edges and heat.
Replace the faulty throttle position or accelerator pedal sensor assembly as identified by testing.
Clean or replace the throttle body if it is sticking or giving erratic feedback, then carry out any required throttle adaptation or relearn.
Correct battery, charging or earth faults that are upsetting the sensor supply.
Update the control unit calibration only if the manufacturer lists it as a fix for this fault on the vehicle.

Can I keep driving?

Medium severity

The car may be driven carefully for a short time, but the intermittent fault can cause sudden loss of power or limp mode, which is a risk in traffic. Get it diagnosed soon and avoid long journeys or overtaking until it is fixed.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.