What is an OBD2 code?

An OBD2 (On-Board Diagnostics) code is a diagnostic trouble code (DTC) generated by your vehicle's computer system when it detects a problem. These codes help identify specific issues with your vehicle's engine, transmission, emissions, or other systems.

How do I read OBD2 codes?

To read OBD2 codes, you'll need an OBD2 scanner. Plug it into your vehicle's OBD2 port (usually located under the dashboard), turn your key to the 'ON' position, and follow your scanner's instructions to retrieve the codes. Each code starts with a letter (P, B, C, or U) followed by four numbers.

What do the different types of OBD2 codes mean?

OBD2 codes are categorized by their first letter: P (Powertrain) for engine and transmission issues, B (Body) for interior systems like airbags, C (Chassis) for mechanical systems like brakes, and U (Network) for computer and module communication problems.

🖨️

Home » OBD2 Codes » C0039

Code C0039

Symptoms

• ABS warning light on

• Traction control light on

• Inconsistent braking performance

Common Causes

• Faulty right rear wheel speed sensor

• Damaged wiring or connectors

• Faulty ABS module

Glossary

ABS: Anti-lock Braking System

OBD-II: On-Board Diagnostics, a system that monitors vehicle performance

Related Codes

• C0040

• C0041

Laymans terms

This code means there's a problem with one of the wheels on your car. It's like when your bike wheel is wobbly and doesn't spin right.

Explanation

C0039 is an OBD-II code indicating an issue with the right rear wheel speed sensor.

Technical description

The C0039 code is set when the Anti-lock Braking System (ABS) module detects a malfunction in the right rear wheel speed sensor or its circuit. This sensor is responsible for monitoring the speed of the wheel and sending this information to the ABS module to help control the braking system.

Diagnosis steps

• Use an OBD-II scanner to verify the code.

• Inspect the right rear wheel speed sensor and its wiring for damage.

• Test the sensor's electrical resistance and output signal.

Repair procedures

• Replace the faulty right rear wheel speed sensor.

• Repair or replace damaged wiring or connectors.

• Replace the ABS module if necessary.

Tools required

• OBD-II scanner

• Multimeter

• Socket set

Estimated repair cost

$100 - $300

Difficulty level

Moderate

Commonly affected vehicles

• Ford F-150

• Chevrolet Silverado

• Toyota Camry

Preventive measures

• Regularly inspect wheel speed sensors.

• Ensure wiring is not exposed to excessive moisture.

• Avoid harsh driving conditions that may damage sensors.

Error code type

Sensor Issue

User experience recommendations

• Drive cautiously until the issue is resolved.

• Avoid sudden braking.

• Get the vehicle inspected by a professional.

Warranty information

Check if your vehicle's warranty covers ABS components.

Historical data

C0039 has been a common issue in vehicles with ABS systems, particularly affecting older models.

Urgency level

Moderate – It affects braking performance, so it should be addressed soon.

Legal and safety notice

Ignoring ABS issues can lead to unsafe driving conditions. Always ensure your vehicle's braking system is functioning properly.

Testing conditions

• Vehicle on a flat surface

• Engine off

Component location

The right rear wheel speed sensor is located near the brake assembly of the rear right wheel.

FAQs

Q: Can I drive with a C0039 code?
A: It's not recommended to drive with this code as it affects your braking system.

Q: How can I reset the ABS light?
A: Fix the underlying issue and use an OBD-II scanner to clear the code.

Last updated: Jan 15, 2026 • Source: internal database

Diagnose Your Check Engine Light