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.

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Home » OBD2 Codes » C0040

Code C0040

Symptoms

• ABS warning light on

• Traction control light on

• Inconsistent speedometer readings

Common Causes

• Faulty right front wheel speed sensor

• Damaged wiring or connectors

• Faulty ABS control module

Glossary

ABS: Anti-lock Braking System

DTC: Diagnostic Trouble Code

Related Codes

• C0035

• C0041

Laymans terms

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

Explanation

The C0040 code indicates an issue with the right front wheel speed sensor.

Technical description

C0040 is a diagnostic trouble code (DTC) for 'Right Front Wheel Speed Sensor Circuit'. This code is set when the ABS module detects a malfunction in the right front wheel speed sensor circuit, which is responsible for monitoring the speed of the wheel and sending this information to the ABS control module.

Diagnosis steps

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

• Inspect the right front wheel speed sensor and its wiring.

• Test the sensor with a multimeter for proper resistance.

Repair procedures

• Replace the right front wheel speed sensor.

• Repair or replace damaged wiring or connectors.

• Replace the ABS control module if necessary.

Tools required

• OBD-II scanner

• Multimeter

• Socket set

Estimated repair cost

$100 - $300

Difficulty level

Moderate

Commonly affected vehicles

• Chevrolet Silverado

• Ford F-150

• Toyota Camry

Preventive measures

• Regularly inspect wheel speed sensors.

• Keep the ABS system clean and free of debris.

• Check wiring and connectors for damage.

Error code type

Sensor Issue

User experience recommendations

• Do not ignore the ABS warning light.

• Have the vehicle inspected by a professional if unsure.

• Avoid hard braking until the issue is resolved.

Warranty information

Check with your vehicle manufacturer for specific warranty coverage related to ABS components.

Historical data

C0040 has been a common code in vehicles with ABS systems, often related to sensor wear or damage.

Urgency level

Moderate – While the vehicle may still be drivable, the ABS system is compromised, affecting safety.

Legal and safety notice

Driving with a malfunctioning ABS system can be dangerous and is not recommended.

Testing conditions

• Vehicle on a flat surface

• Ignition in the 'On' position

Component location

The right front wheel speed sensor is located near the wheel hub assembly on the front passenger side.

FAQs

Q: Can I drive with a C0040 code?
A: You can drive, but it's not safe as your ABS system may not work properly.

Q: How do I reset the ABS light?
A: Fix the underlying issue first, then use an OBD-II scanner to clear the code.

Last updated: Oct 28, 2025 • Source: internal database

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