P0229 medium Severity

P0229: Throttle/Pedal Position Sensor/Switch “C” Circuit Intermittent

Intermittent loss of throttle signal leading to erratic throttle response and possible limp-mode activation

Overview

P0229 is an OBD-II powertrain DTC for intermittent faults in the throttle or accelerator pedal position sensor “C” circuit, causing erratic signal voltage to the ECM.

Common Symptoms

  • Check engine light illuminated
  • Poor or erratic throttle response
  • Intermittent loss of engine power / limp mode
  • Unstable idle
  • Possible engine stall at low speeds

Most Common Causes

Intermittent or poor electrical connection at TPS or APP sensor C circuit high

Connector corrosion, loose pins, or intermittent wiring contact.

Damaged or broken wiring harness for TPS/APP sensor C circuit high

Chafed insulation, pinched wires causing intermittent signal loss.

Faulty throttle position sensor or accelerator pedal position sensor (C circuit) medium

Internal sensor failure producing erratic voltage.

ECM/PCM internal input circuit fault low

Rare compared to wiring/sensor issues; requires module testing.

Diagnostic Steps

  1. Connect OBD-II scanner and retrieve current and pending codes including live data
    Expected: P0229 present; note freeze frame data
    Interpretation: Baseline for diagnosis; confirms intermittent nature
  2. Visually inspect wiring and connectors at throttle and pedal position sensors
    Expected: No corrosion, tight pins, no damage
    Interpretation: Good connector condition reduces likelihood of wiring issues
  3. Perform a wiggle test on sensor harness with engine running while monitoring live throttle/APP C circuit voltage
    Expected: Stable voltage trace without drops
    Interpretation: Voltage fluctuation indicates intermittent circuit fault
  4. Measure voltage and continuity on sensor C circuit back-to-back between sensor and ECM
    Expected: Correct reference voltage (approx 0.5–4.5 V) and solid continuity
    Interpretation: Out-of-spec values pinpoint wiring or sensor issue
  5. Substitute known good sensor or bench-test sensor if wiring tests good
    Expected: Sensor outputs consistent voltage with pedal movement
    Interpretation: Failure to improve indicates ECM or harness issue

Repair Solutions

Clean and secure electrical connectors; apply dielectric grease medium
Estimated Cost: $10 - $50

Effective for corrosion/loose connection issues

Repair or replace damaged wiring harness sections medium
Estimated Cost: $50 - $250

Costs vary with wiring complexity

Replace throttle position sensor or accelerator pedal position sensor medium
Estimated Cost: $100 - $400

Price depends on vehicle make/model

ECM reprogramming or replacement if internal fault confirmed hard
Estimated Cost: $600 - $1200

High cost; verify all other causes before ECM work

Common Misdiagnoses

Avoid these common diagnostic mistakes:

  • Misinterpreting random intermittent connector corrosion as sensor failure
  • Incorrectly diagnosing PCM fault without thorough wiring tests
  • Confusing related throttle/pedal circuit codes like P2135 with P0229

Frequently Asked Questions

Can you explain the meaning of P0229?

Throttle/Pedal Position Sensor/Switch “C” Circuit Intermittent is the standard definition for P0229. This diagnostic code is triggered when the ECU detects a problem in the Sensors.

Can P0229 cause engine damage?

The P0229 code is considered medium severity. Intermittent loss of throttle signal leading to erratic throttle response and possible limp-mode activation

What happens when the P0229 code is active?

The most typical signs are: Check engine light illuminated, Poor or erratic throttle response, Intermittent loss of engine power / limp mode.

What causes the P0229 code?

Potential culprits include: Intermittent or poor electrical connection at TPS or APP sensor C circuit, Damaged or broken wiring harness for TPS/APP sensor C circuit, Faulty throttle position sensor or accelerator pedal position sensor (C circuit). A proper diagnosis is recommended.

Estimated repair costs for different causes of P0229

It depends on what needs to be fixed. Clean and secure electrical connectors; apply dielectric grease repairs are cheaper (~$50), while ECM reprogramming or replacement if internal fault confirmed repairs are on the higher end (~$1200).

Is the P0229 code specific to Mercedes?

This is a universal code. You might see P0229 on Ford, Chevrolet, Toyota, Honda, Nissan, or any other OBD-II vehicle.

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