OBD Guide
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C129B

Brake Pedal Position Sensor 3 Circuit High Input

C129B is an OBD-II diagnostic trouble code meaning: Brake Pedal Position Sensor 3 Circuit High Input. Common causes: short circuit in the sensor circuit to positive, sensor circuit open. Estimated repair cost: $56–167.

Severity
⚠️ Medium
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$56–167 (est.)

Symptoms

  • The brake system fault indicator is on
  • Unstable ABS/ESP operation
  • Problems with cruise control

Causes

  • Short circuit in the sensor circuit to positive
  • Sensor circuit open
  • Malfunction of the brake pedal position sensor
  • Wiring Harness Problems
  • Malfunction of the brake system control unit

How to Fix

  1. Check the integrity of the wiring harness
  2. Check the voltage and resistance in the sensor circuit
  3. Replace the brake pedal position sensor if necessary
  4. Check and replace the brake system control unit if necessary

Related codes

C129AC129CC129D

FAQ

What does the C129B code mean?

C129B is an OBD-II diagnostic trouble code that indicates: Brake Pedal Position Sensor 3 Circuit High Input

What causes a C129B error code?

The most common causes of C129B include: Short circuit in the sensor circuit to positive; Sensor circuit open; Malfunction of the brake pedal position sensor; Wiring Harness Problems.

How do I fix a C129B diagnostic trouble code?

To fix C129B: Check the integrity of the wiring harness. Check the voltage and resistance in the sensor circuit. Replace the brake pedal position sensor if necessary. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with C129B?

Do not drive — repair immediately

How much does it cost to fix C129B?

The estimated repair cost for C129B is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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