C0086 - Vehicle Speed Sensor 'A' Range/Performance Problem in GM Models

Quick Answer

C0086 means: DTC C0086 indicates a problem with the vehicle speed sensor 'A', affecting speed readings and vehicle performance.

Fix: Check and replace faulty components Cost: $150 - $300 Time: 90-180 minutes

Can I drive with C0086? Immediate attention is advised to prevent further damage to the transmission.

Common Questions

What does C0086 mean and how does it affect my car?

C0086 indicates an issue with the vehicle speed sensor 'A', which can lead to inaccurate speed readings affecting your vehicle's performance. If ignored, it may cause transmission problems and decrease fuel efficiency.

What are the most common causes of C0086 and how much does it cost to fix?

Common causes include a faulty speed sensor, wiring issues, or a malfunctioning ECU. Repair costs typically range from $150 to $300 for sensor replacement and $100 to $200 for wiring repairs.

Can I drive my car with C0086 or should I stop immediately?

It's advisable to stop driving your vehicle if you see the C0086 code. Continuing to drive can lead to further transmission damage and safety hazards.

How can I diagnose C0086 myself using GeekOBD APP?

You can use the GeekOBD APP to scan for DTCs, view freeze frame data for the C0086 code, and check the live data of the speed sensor to identify any inconsistencies.

What vehicles are most commonly affected by C0086?

C0086 is commonly found in GM models such as the Chevrolet Silverado (2007-2018) and the Cadillac Escalade (2007-2018).

How can I prevent C0086 from happening again?

Regular maintenance, including checking wiring and connections, can help prevent issues with the speed sensor. Additionally, keep the area around the sensor clean and free of debris.

What is C0086?

The diagnostic trouble code (DTC) C0086 indicates a range or performance issue with the vehicle speed sensor 'A'. This code is primarily found in General Motors (GM) vehicles, such as the Chevrolet Silverado, GMC Sierra, and Cadillac Escalade, typically from the years 2007 to 2018. The vehicle speed sensor is crucial for providing accurate speed readings to the engine control unit (ECU) and other systems. When this sensor fails or experiences inconsistencies, it can result in erratic speed readings, which can affect the vehicle's performance, fuel efficiency, and safety. Drivers may notice symptoms such as the check engine light illuminating, inconsistent speedometer readings, or even transmission issues as the vehicle struggles to shift correctly. Ignoring this code can lead to more severe problems, including transmission damage or reduced fuel economy, making timely diagnosis and repair essential for maintaining vehicle functionality.

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

Symptoms

Common symptoms when C0086 is present:

  • Check engine light remains illuminated, indicating a fault in the vehicle's systems.
  • Inconsistent or erratic speedometer readings, leading to confusion during driving.
  • Transmission may hesitate or shift harshly, especially during acceleration or deceleration.
  • Vehicle may experience reduced fuel efficiency as the engine struggles to adapt to inaccurate speed data.
  • The cruise control system may disengage unexpectedly due to faulty speed readings.

Possible Causes

Most common causes of C0086 (ordered by frequency):

  1. {'cause': 'Faulty vehicle speed sensor', 'likelihood': '70%', 'details': 'The sensor itself may be damaged or malfunctioning, leading to incorrect speed readings.'}
  2. {'cause': 'Wiring issues or poor connections', 'details': 'Damaged wires or corroded connectors can prevent the sensor from transmitting accurate data to the ECU.'}
  3. {'cause': 'Faulty ECU', 'details': "In some cases, the vehicle's engine control unit may not process the sensor data correctly, leading to false readings."}
  4. {'cause': 'Mechanical issues within the transmission', 'details': 'Less commonly, internal transmission problems can affect sensor performance.'}
  5. {'cause': 'Contaminated sensor from debris or moisture', 'details': "Environmental factors can cause dirt or moisture to interfere with the sensor's operation."}

C0086 Repair Costs

Cost Breakdown by Repair Type

Speed Sensor Replacement

Replacing the faulty vehicle speed sensor.

  • Total: $150 - $300
  • Success rate: 90%
Wiring Repair

Repairing or replacing damaged wiring or connectors.

  • Total: $100 - $200
  • Success rate: 85%
Money-Saving Tips for C0086
  • 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 C0086 Diagnosis Process

Follow these systematic steps to accurately diagnose C0086. 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 the vehicle speed sensor and associated wiring (20-30 minutes)

Step 3: Component testing - Use a multimeter or specific diagnostic tools to test the vehicle speed sensor and associated wiring (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 of the speed sensor after repairs and clear codes (10-15 minutes)

Step 4: System function test - Verify proper operation of the speed sensor after repairs and clear codes (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 proper speed readings (15-20 minutes)

Step 5: Road test verification - Drive the vehicle under various conditions to confirm repair success and proper speed readings (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: 2008 Chevrolet Silverado C0086 Repair

Vehicle: 2008 Chevrolet Silverado, 120,000 miles

Problem: Customer reported the check engine light and inconsistent speedometer readings.

Diagnosis: After scanning the vehicle, C0086 was confirmed. The speed sensor was tested and found to be faulty.

Solution: Replaced the vehicle speed sensor and cleared the codes.

Cost: $220 (parts: $120, labor: $100)

Result: The speedometer readings stabilized, and the check engine light remained off after the repair.

Case Study 2: 2015 GMC Sierra Transmission Issues Related to C0086

Vehicle: 2015 GMC Sierra, 80,000 miles

Problem: Customer experienced harsh shifting and check engine light illumination.

Diagnosis: C0086 was retrieved; wiring was found damaged due to corrosion.

Solution: Repaired the wiring harness and replaced the speed sensor.

Cost: $300 (parts: $200, labor: $100)

Result: The transmission shifted smoothly, and the customer reported improved performance.

Diagnose C0086

Use GeekOBD APP for professional diagnosis!

  • Real-time data monitoring
  • Advanced diagnostic features
  • Step-by-step repair guidance
  • Professional-grade analysis
Download GeekOBD APP Get MOBD Adapter

Code Information

Code: C0086
System: Chassis (ABS, Steering, Suspension)
Severity: HIGH
Category: Chassis Codes