AutoCodes – Generic – C129A

C129A Code - Brake Pedal Position Sensor 3 Circuit Low Input

Quick Answer

The Electronic Brake Control Module (EBCM) uses inputs from the electronic brake control brake pedal position sensor to determine when the brake is applied and how much force is used. Common causes include Faulty Brake Pedal Position Sensor, Brake Pedal Position Sensor harness is open or shorted, Brake Pedal Position Sensor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: C129A indicates Brake Pedal Position Sensor 3 Circuit Low Input.
Common causes: Common causes include Faulty Brake Pedal Position Sensor, Brake Pedal Position Sensor harness is open or shorted, Brake Pedal Position Sensor circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 1,006

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Sep 04, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code C129A Description

The Electronic Brake Control Module (EBCM) uses inputs from the electronic brake control brake pedal position sensor to determine when the brake is applied and how much force is used. The electronic brake control module monitors when the driver's foot is on the brake and locks the offset. The offset is locked when 3 out of the 4 inputs indicate the brake pedal is applied. The 4 inputs are brake pedal travel 1, brake pedal travel 2, master cylinder pressure sensor, and the brake pedal position sensor. These inputs are used to determine the driver's braking intent which is used to the control amount of pressure applied to the wheels.

OBDII Code C129A - Brake Pedal Position Sensor 3 Circuit Low Input - AutoCodes.com — C129A Code - Brake Pedal Position Sensor 3 Circuit Low Input

What does this mean?

What are the Possible Causes of the DTC C129A?

Faulty Brake Pedal Position Sensor
Brake Pedal Position Sensor harness is open or shorted
Brake Pedal Position Sensor circuit poor electrical connection
Faulty Electronic Brake Control Module (EBCM)

How to Fix the DTC C129A?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the C129A code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the C129A code?

Need more information on how to fix the C129A code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the C129A code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

C129A Buick — Brake Pedal Position Sensor 3 Circuit Low Input
C129A Cadillac — Brake Pedal Position Sensor 3 Circuit Low Input
C129A Chevrolet — Brake Pedal Position Sensor 3 Circuit Low Input
C129A GMC — Brake Pedal Position Sensor 3 Circuit Low Input

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about C129A Code

1. What are the common symptoms of OBDII code C129A (Brake Pedal Position Sensor 3 Circuit Low Input)?

- Common symptoms include issues with the brake pedal functionality, such as the brake lights staying on or off when they shouldn't, difficulty shifting gears, or the vehicle not starting.

2. What are the possible causes of OBDII code C129A?

- The code C129A can be triggered by a faulty brake pedal position sensor, damaged wiring or connectors related to the sensor, or a problem with the sensor circuit itself.

3. How can I diagnose the cause of OBDII code C129A?

- Diagnosing the code involves checking the brake pedal position sensor, inspecting the wiring and connectors for any damage, and using a diagnostic scanner to read the code and monitor sensor data.

4. Can OBDII code C129A be fixed without professional help?

- If you have experience with automotive repairs and access to the necessary tools, you may be able to fix the issue yourself by replacing the brake pedal position sensor or repairing any damaged wiring or connectors.

5. Is it safe to drive with OBDII code C129A present?

- It is not recommended to drive with this code present, as it can affect the proper functioning of the brake system and potentially compromise your safety on the road.

6. How much does it typically cost to repair OBDII code C129A?

- The cost of repairing this code can vary depending on the cause of the issue, but it may range from $100 to $300 for parts and labor if you take your vehicle to a professional mechanic.

7. Will resetting the OBDII code C129A make it go away permanently?

- Resetting the code without addressing the underlying issue will not make it go away permanently. It is important to diagnose and fix the root cause of the problem to prevent the code from reoccurring.

8. Can a malfunctioning brake pedal position sensor cause other problems in the vehicle?

- Yes, a malfunctioning brake pedal position sensor can cause issues with the brake system, transmission shifting, and overall vehicle performance if not addressed promptly.

9. Are there any preventive measures to avoid triggering OBDII code C129A?

- Regularly inspecting the brake pedal position sensor, keeping an eye on brake system functionality, and addressing any warning signs promptly can help prevent the occurrence of code C129A.

10. How long does it typically take to repair OBDII code C129A?

- The repair time for OBDII code C129A can vary depending on the extent of the issue and the availability of parts, but it may take anywhere from 1 to 3 hours for a professional mechanic to diagnose and fix the problem.