P0229 The signal from the third throttle or pedal position sensor (C) drops out or jumps now and then rather than staying wrong.

Throttle/pedal position sensor C circuit intermittent

P0229 in short

P0229 means the computer has found an intermittent fault in the circuit of throttle or pedal position sensor C. Wiring, connectors and the sensor itself are the usual causes. Power may be reduced, so get it checked soon and stop if the engine loses power while you drive.

Electronic throttles use several position sensors so the computer can check them against each other. P0229 is set for sensor C: The signal from the third throttle or pedal position sensor (C) drops out or jumps now and then rather than staying wrong.

TroubleCodes.net says the usual causes are wiring or connector damage and a failed sensor, with throttle body wear or carbon and the computer itself far less likely.

Most likely causes

These are general causes for this code across vehicles. None is specific to one make or model.

  1. Damaged, corroded or loose wiring or connector

    Common general cause
    Why it ranks here
    TroubleCodes.net lists wiring and connector damage first for this code, and circuit faults are most often an electrical connection problem.
    What would change this
    Rises if the signal jumps when the harness or connector is moved. Falls if the connector and harness check clean.

  2. Failed throttle or pedal position sensor

    Common general cause
    Why it ranks here
    TroubleCodes.net lists defective throttle or pedal sensors; sensors are often built into the throttle body or pedal assembly.
    What would change this
    Rises if wiring and reference voltage test good but the signal is still wrong. Falls if the circuit fault is found first.
    How to test the electronic throttle body

  3. Throttle body wear or carbon buildup

    Possible — needs testing
    Why it ranks here
    TroubleCodes.net lists mechanical wear and carbon restricting the throttle plate, but this ranks below electrical causes.
    What would change this
    Rises if the throttle plate is visibly sticky or dirty. Falls if it moves freely.
    How to test the electronic throttle body

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read all stored codes and watch the throttle and pedal position sensor values on a scan tool while slowly pressing the pedal.

    Low riskTool: OBD-II scan tool

    • IfSensor C reading jumps, drops out or is stuck

      It meansLook at the wiring and connector.

      Go to step 2

    • IfReading is smooth and steady

      It meansThe fault may be intermittent or heat related; check the harness anyway.

      Go to step 2

  2. Look over the sensor connector and harness for corrosion, damage and loose pins, and wiggle the harness while watching the reading.

    Use cautionTool: Scan tool, flashlight

    Warning:Keep fingers out of the throttle bore with the ignition on; an electronic throttle can move on its own.

  3. Measure reference voltage, signal and ground at the sensor connector against the service manual, and check resistance.

    Best left to a shopTool: Digital multimeter

    Warning:Back-probe gently and never short the reference pin to ground; that can damage the engine computer.

Symptoms

  • Check engine light
  • Reduced power or slow acceleration
  • Rough idle or hard starting
  • Hesitation or stalling Gets more serious: stop and have it checked.

How to fix

Parts and cost context

  • Electronic throttle body:The sensor is usually part of the throttle body, so it is replaced as a unit and a throttle relearn is needed. Labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Buick

  • 2021–2023 · Envision

    Supported by vehicle data

    Buick bulletin 22-NA-079 covers installing a cover for poor engine performance in extremely cold weather on LSY engines, with charge air cooler icing and P0229. Whether it is still current is not verified.

  • 22-NA-079Status unverified

    Cover for cold-weather poor performance and charge air cooler icing, LSY engines

    2021–2023envision · issued · NHTSA 10235586

    Technical bulletin on installing a cover for poor engine performance in extremely cold weather on LSY engines, with charge air cooler icing and the check engine light on with P0229. Only the NHTSA summary was read, not the bulletin itself.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • P0225The computer sees a signal from the third throttle or pedal position sensor (C) that does not make sense for the conditions, so it flags a circuit fault.

    Shares causes Common general cause

    P0225 is the same sensor C circuit with a different fault type.

  • P0226The signal from the third throttle or pedal position sensor (C) is in range but does not match what the engine is doing.

    Shares causes Common general cause

    P0226 is the same sensor C circuit with a different fault type.

  • P0227The signal from the third throttle or pedal position sensor (C) is lower than the circuit should ever produce.

    Shares causes Common general cause

    P0227 is the same sensor C circuit with a different fault type.

All Electronic throttle and accelerator pedal codes

Sources and review

  1. P0229 - Throttle/Pedal Position Sensor/Switch C Circuit Intermittent — TroubleCodes.net
  2. On-Board Diagnostic Trouble Codes (generic code title list) — Delaware Division of Motor Vehicles
  3. 22-NA-079: Cover for cold-weather poor performance and charge air cooler icing, LSY engines — Buick
Last reviewed
Written by
Saurabh K.
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