Engine-CodesGMC – C12F8 GMC

C12F8 GMC Code - Brake Pedal Position Sensor 3 Not Plausible

Quick Answer

The C12F8 GMC diagnostic trouble code indicates that the Brake Pedal Position Sensor 3 is not providing plausible data to the vehicle's electronic control unit (ECU). Common causes include Faulty brake pedal position sensor, Wiring or electrical connection issues, Corrosion or damage to sensor components. 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
C12F8 GMC indicates Brake Pedal Position Sensor 3 Not Plausible.
Common causes
Common causes include Faulty brake pedal position sensor, Wiring or electrical connection issues, Corrosion or damage to sensor components.
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.
Table of contents Created and updated by William Orellana on Sep 13, 2024
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Code C12F8 GMC Description

The C12F8 GMC diagnostic trouble code indicates that the Brake Pedal Position Sensor 3 is not providing plausible data to the vehicle's electronic control unit (ECU). The brake pedal position sensor is a crucial component that monitors the position of the brake pedal and sends this information to the ECU. This data is used by the ECU to determine when to activate the brake lights, control the vehicle's braking system, and engage safety features such as traction control and stability control.

OBDII Code C12F8 GMC - Brake Pedal Position Sensor 3 Not Plausible
C12F8 GMC Code - Brake Pedal Position Sensor 3 Not Plausible

Common Causes of C12F8 GMC

  1. Faulty brake pedal position sensor
  2. Wiring or electrical connection issues
  3. Corrosion or damage to sensor components
  4. ECU software malfunction
  5. Mechanical issues with the brake pedal assembly

Symptoms of C12F8 GMC

  1. Illumination of the brake warning light on the dashboard
  2. Inconsistent or delayed brake light activation
  3. Decreased responsiveness of the braking system
  4. Traction control or stability control warning lights appearing on the dashboard
  5. Difficulty engaging cruise control or other safety features

How to Fix C12F8 GMC

  1. Begin by diagnosing the specific cause of the issue using a diagnostic scanner to read the fault codes and pinpoint the problem.
  2. Inspect the brake pedal position sensor and its wiring for any visible damage, corrosion, or loose connections. Replace or repair any damaged components.
  3. Test the sensor's functionality using a multimeter to ensure it is sending accurate data to the ECU.
  4. If necessary, reprogram the ECU to recalibrate the sensor and ensure proper communication between the sensor and the vehicle's systems.
  5. Clear the fault codes from the ECU's memory and test drive the vehicle to verify that the issue has been resolved.

Cost to Fix C12F8 GMC

The cost of repairing a Brake Pedal Position Sensor 3 Not Plausible issue can vary depending on the specific cause of the problem and the vehicle's make and model. In general, the cost of parts for this repair can range from $50 to $200, while labor costs can range from $100 to $300. Overall, the total repair cost can be estimated to be between $150 and $500. It is important to note that labor rates at auto repair shops can vary, so it is advisable to check with local shops for a more accurate estimate based on your location and vehicle type.

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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 C12F8 GMC Code

1. What does the OBDII code C12F8 on a GMC vehicle mean?

The C12F8 code indicates that the Brake Pedal Position Sensor 3 is providing a signal that is not plausible or consistent with expected values.

2. What are the symptoms of the C12F8 code on a GMC?

Common symptoms include the illumination of the ABS or traction control warning light, reduced braking performance, and erratic brake system behavior.

3. What causes the C12F8 code to appear?

The code can be caused by a faulty brake pedal position sensor, damaged wiring or connectors, or issues with the vehicle’s ABS control module.

4. Can I drive my GMC with the C12F8 code active?

While the vehicle may still be drivable, it’s not recommended as braking system performance and safety features like ABS or traction control may be compromised.

5. How do I diagnose the C12F8 code on my GMC?

Diagnose the code by scanning for additional fault codes, inspecting the brake pedal position sensor and its wiring, and testing the sensor’s output with a multimeter.

6. How do I fix the C12F8 code on a GMC vehicle?

Repairs may involve replacing the faulty brake pedal position sensor, repairing damaged wiring, or recalibrating the ABS control module.

7. Is the brake pedal position sensor the same as a brake light switch?

No, the brake pedal position sensor monitors the pedal’s position for the ABS and traction control systems, while the brake light switch controls the brake lights.

8. How much does it cost to fix the C12F8 code on a GMC?

Repair costs vary, but replacing the brake pedal position sensor typically costs between $150 and $300, including parts and labor.

9. Can a dead battery cause the C12F8 code to appear?

While unlikely, a weak or dead battery can cause voltage irregularities that might trigger sensor-related codes, though it’s not a common cause for C12F8.

10. Do I need to recalibrate the brake pedal position sensor after replacement?

Yes, many GMC vehicles require the brake pedal position sensor to be recalibrated after replacement to ensure proper function.

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