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Engine-Codes – Generic – C191B

C191B Code - Rear Vehicle Speed Signal

Quick Answer

The C191B diagnostic trouble code (DTC) refers to a problem with the rear vehicle speed signal in the vehicle's electronic control system. Common causes include Faulty rear wheel speed sensor, Damaged wiring or connectors in the rear vehicle speed signal circuit, Corrosion or contamination in the sensor or wiring. 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
C191B indicates Rear Vehicle Speed Signal.
Common causes
Common causes include Faulty rear wheel speed sensor, Damaged wiring or connectors in the rear vehicle speed signal circuit, Corrosion or contamination in the sensor or wiring.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 10, 2024
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Code C191B Description

The C191B diagnostic trouble code (DTC) refers to a problem with the rear vehicle speed signal in the vehicle's electronic control system. The rear vehicle speed signal is crucial for various systems in the vehicle, including the anti-lock braking system (ABS), traction control system, and stability control system. This signal helps these systems to accurately monitor the vehicle's speed and make necessary adjustments to ensure optimal performance and safety.

OBDII Code C191B - Rear Vehicle Speed Signal
C191B Code - Rear Vehicle Speed Signal

Common Causes of C191B

  1. Faulty rear wheel speed sensor
  2. Damaged wiring or connectors in the rear vehicle speed signal circuit
  3. Corrosion or contamination in the sensor or wiring
  4. Electronic control module (ECM) malfunction
  5. Vehicle speed sensor alignment issue

Symptoms of C191B

  1. ABS warning light illuminated on the dashboard
  2. Traction control system malfunction
  3. Vehicle stability control system engaged unexpectedly
  4. Inaccurate speedometer readings
  5. Harsh shifting in automatic transmission vehicles

How to Fix C191B

  1. Diagnose the issue using a diagnostic scanner to pinpoint the exact cause of the rear vehicle speed signal problem.
  2. Inspect the rear wheel speed sensor and its wiring for any damage or corrosion. Replace or repair as necessary.
  3. Check the alignment of the vehicle speed sensor and adjust if needed.
  4. Test the system to ensure the rear vehicle speed signal is being accurately transmitted to the ECM and related systems.
  5. Clear the DTC and test drive the vehicle to verify that the issue has been resolved.

Cost to Fix C191B

The cost of repairing a rear vehicle speed signal issue can vary depending on the specific cause of the problem and the parts and labor required for the repair. On average, the cost of replacing a faulty rear wheel speed sensor can range from $100 to $300, including parts and labor. However, additional costs may apply if other components need to be replaced or if extensive diagnostic work is required. It is recommended to consult with a qualified mechanic or auto repair shop for a more accurate cost estimate based on the specific vehicle make and model. Keep in mind that diagnostic time and labor rates can vary, so it's advisable to inquire about these costs upfront.

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Code C191B Information for Specific Makes

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 C191B Code

1. What are the common symptoms of OBDII code C191B (Rear Vehicle Speed Signal)?

- Common symptoms include erratic speedometer readings, ABS or traction control system malfunctions, and illumination of the ABS warning light.

2. What are the possible causes of OBDII code C191B?

- Possible causes include a faulty rear wheel speed sensor, damaged wiring or connectors in the rear speed sensor circuit, or a malfunctioning ABS control module.

3. How can I diagnose the issue related to OBDII code C191B?

- Diagnose the issue by performing a visual inspection of the rear wheel speed sensor and its wiring, checking for loose connections, and using an OBDII scanner to read the trouble codes and data related to the rear vehicle speed signal.

4. Can I drive my vehicle with OBDII code C191B?

- It is not recommended to drive your vehicle with OBDII code C191B as it can affect the proper functioning of the ABS and traction control systems, compromising the vehicle's safety.

5. How can I repair OBDII code C191B?

- Repair the issue by replacing the faulty rear wheel speed sensor, repairing damaged wiring or connectors, or reprogramming the ABS control module as recommended by the manufacturer.

6. Are there any DIY tips for fixing OBDII code C191B?

- DIY tips include checking and cleaning the rear wheel speed sensor connectors, ensuring proper wheel alignment, and conducting a road test to verify the repair.

7. How much does it cost to fix OBDII code C191B?

- The cost to fix OBDII code C191B can vary depending on the cause of the issue, but it typically ranges from $100 to $300 for parts and labor.

8. Can OBDII code C191B cause other problems in my vehicle?

- Yes, OBDII code C191B can cause issues with the ABS and traction control systems, affecting the vehicle's stability and handling on the road.

9. Will OBDII code C191B cause my vehicle to fail an emissions test?

- OBDII code C191B is not directly related to emissions, but it can cause the vehicle to fail an emissions test if it leads to other malfunctions affecting the engine control system.

10. How can I prevent OBDII code C191B from recurring in the future?

- To prevent OBDII code C191B from recurring, ensure regular maintenance of the ABS and traction control systems, inspect the wheel speed sensors periodically, and address any issues promptly.

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