C0120 - ABS Sensor Malfunction in Common Vehicles Like Chevy Silverado and GMC Sierra

Quick Answer

C0120 means: C0120 indicates an issue with the ABS sensor circuit.

Fix: Check and replace faulty components Cost: $100 - $300 Time: 90-180 minutes

Can I drive with C0120? Immediate action is advised as it affects braking safety.

Common Questions

What does C0120 mean and how does it affect my car?

The C0120 code signals a problem with your vehicle's ABS sensor circuit, which can lead to ABS system failure. This affects your car's braking performance and can increase stopping distances, especially in adverse conditions. It's essential to address this issue promptly to ensure your safety on the road.

What are the most common causes of C0120 and how much does it cost to fix?

Common causes include a faulty ABS wheel speed sensor (around $100-$300 to replace), damaged wiring, or a malfunctioning ABS control module (up to $800). Regular checks can prevent these issues from escalating.

Can I drive my car with C0120 or should I stop immediately?

It's not safe to drive with the C0120 code present, as it indicates potential braking issues. You should stop driving and get your vehicle inspected to prevent further damage or safety risks.

How can I diagnose C0120 myself using GeekOBD APP?

To diagnose C0120, start by using the GeekOBD APP to scan for codes. It will provide detailed information about the ABS system's status. You can also check the freeze frame data to understand the conditions under which the code was triggered.

What vehicles are most commonly affected by C0120?

The C0120 code is frequently found in vehicles such as the 2003-2007 Chevrolet Silverado and GMC Sierra, as well as various models from Ford and Dodge during the same time frame. Always check for any recalls related to the ABS system for your specific vehicle.

How can I prevent C0120 from happening again?

Regular maintenance, including checking the ABS system and cleaning the wheel speed sensors, can help prevent C0120. Additionally, avoid driving over rough terrain that could damage the sensors or wiring.

What is C0120?

The diagnostic trouble code (DTC) C0120 indicates a malfunction in the Anti-lock Brake System (ABS) sensor circuit. This code may be triggered when the ABS control module detects an issue with the wheel speed sensors or their associated wiring. Typically, this affects vehicles like the 2003-2007 Chevrolet Silverado and GMC Sierra, which are prone to such issues due to environmental exposure and wear over time. When the C0120 code is present, it can lead to the ABS warning light illuminating on the dashboard, indicating that the system may not function correctly. This can compromise your vehicle's braking performance, especially under hard braking or adverse weather conditions, making it crucial to address promptly. Additionally, a malfunctioning ABS can lead to longer stopping distances and decreased overall safety. Ignoring this code can cause further damage to the braking system and may lead to costly repairs down the line. Therefore, understanding the implications of DTC C0120 and taking immediate action is vital for maintaining your vehicle's safety and reliability.

System: C - Chassis (ABS, Steering, Suspension)

Symptoms

Common symptoms when C0120 is present:

  • The ABS warning light is illuminated on the dashboard, indicating the system is not functioning.
  • You may notice the brakes feeling different during hard stops, such as being more sluggish or unresponsive.
  • Increased stopping distances, particularly noticeable during wet or slippery conditions, which can compromise safety.
  • The vehicle may exhibit a pulsating brake pedal feel when attempting to brake, signifying ABS issues.
  • You might experience erratic brake performance or unusual noises during braking, suggesting sensor malfunction.

Possible Causes

Most common causes of C0120 (ordered by frequency):

  1. The most common cause of C0120 is a faulty ABS wheel speed sensor, with a likelihood of around 60%. These sensors can fail due to wear, dirt buildup, or electrical issues.
  2. A second common cause is damaged wiring or connectors in the ABS circuit, which can occur due to vehicle age or exposure to harsh conditions.
  3. A less frequent cause could be a malfunctioning ABS control module, which can lead to a complete system failure if not addressed.
  4. In some cases, the code may be triggered by a programming error or system reset, which is less common but still possible.
  5. Finally, rare issues like corrosion at connection points or internal sensor failure can occur, warranting thorough inspection.

C0120 Repair Costs

Cost Breakdown by Repair Type

ABS Wheel Speed Sensor Replacement

Replacing a faulty ABS wheel speed sensor to restore proper braking functionality.

  • Total: $100 - $300
  • Success rate: 90%
Wiring Repair

Repairing damaged wiring or connectors in the ABS circuit to ensure proper electrical flow.

  • Total: $50 - $150
  • Success rate: 85%
ABS Control Module Replacement

Replacing the ABS control module if the current one is malfunctioning.

  • Total: $400 - $800
  • Success rate: 75%
Money-Saving Tips for C0120
  • Start with the most common and least expensive repairs first
  • Use GeekOBD APP to confirm diagnosis before replacing expensive parts
  • Consider preventive maintenance to avoid future occurrences
  • Compare prices for OEM vs aftermarket parts based on your needs
  • Address the issue promptly to prevent more expensive secondary damage

Diagnostic Steps

Professional C0120 Diagnosis Process

Follow these systematic steps to accurately diagnose C0120. Each step builds on the previous one to ensure accurate diagnosis.

Step 1: Step 1: Initial visual inspection - Check for obvious signs like damaged wiring, loose connections, or corrosion (5-10 minutes)

Step 1: Initial visual inspection - Check for obvious signs like damaged wiring, loose connections, or corrosion (5-10 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 2: Step 2: OBD2 scan with GeekOBD APP - Retrieve all codes and freeze frame data to understand the fault context (10-15 minutes)

Step 2: OBD2 scan with GeekOBD APP - Retrieve all codes and freeze frame data to understand the fault context (10-15 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 3: Step 3: Component testing - Use a multimeter or specific diagnostic tools to test suspected components, particularly the wheel speed sensors (20-30 minutes)

Step 3: Component testing - Use a multimeter or specific diagnostic tools to test suspected components, particularly the wheel speed sensors (20-30 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 4: Step 4: System function test - Verify proper operation after repairs and clear codes to reset the ABS system (10-15 minutes)

Step 4: System function test - Verify proper operation after repairs and clear codes to reset the ABS system (10-15 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 5: Step 5: Road test verification - Drive the vehicle under various conditions to confirm repair success and ensure the ABS light does not return (15-20 minutes)

Step 5: Road test verification - Drive the vehicle under various conditions to confirm repair success and ensure the ABS light does not return (15-20 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.

Important Notes

  • Always verify the repair with GeekOBD APP after completing diagnostic steps
  • Clear codes and test drive to ensure the problem is resolved
  • Address underlying causes to prevent code recurrence

Real Repair Case Studies

Case Study 1: Chevy Silverado ABS Sensor Replacement

Vehicle: 2005 Chevrolet Silverado 1500, 120,000 miles

Problem: Customer reported ABS warning light illuminated and unusual braking behavior.

Diagnosis: After scanning with GeekOBD APP, C0120 was confirmed. Visual inspection revealed a damaged wheel speed sensor.

Solution: Replaced the faulty wheel speed sensor and cleared the DTC, restoring ABS functionality.

Cost: $250 (sensor $150, labor $100)

Result: The ABS light remained off after the repair, and the customer reported improved braking performance.

Case Study 2: GMC Sierra Wiring Repair

Vehicle: 2006 GMC Sierra 2500 HD, 90,000 miles

Problem: ABS light on and erratic brake performance experienced by the owner.

Diagnosis: Diagnostic testing revealed C0120 due to damaged wiring in the ABS circuit.

Solution: Repaired the damaged wiring and ensured all connections were secure.

Cost: $100 (wiring repair, labor included)

Result: Post-repair road tests confirmed the ABS system was functioning correctly, and the warning light stayed off.

Diagnose C0120

Use GeekOBD APP for professional diagnosis!

  • Real-time data monitoring
  • Advanced diagnostic features
  • Step-by-step repair guidance
  • Professional-grade analysis
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Code Information

Code: C0120
System: Chassis (ABS, Steering, Suspension)
Severity: HIGH
Category: Chassis Codes