Can I still drive with the ABS and traction control lights on?

In most cases your brakes will still work normally, but you lose the safety net of ABS and traction control. We recommend getting it checked promptly, especially in wet or icy conditions.

How much does it cost to replace a wheel speed sensor?

A wheel speed sensor is generally a straightforward and affordable fix compared to an ABS module replacement. Exact pricing depends on your vehicle make and model — call us on 020 8803 1231 for a quote.

Will an ABS fault cause my car to fail its MOT?

Yes. An illuminated ABS warning light is a Major MOT failure item since 2018. The car will not pass until the fault is diagnosed and repaired.

Can a bad wheel bearing cause the ABS light to come on?

Yes. On many vehicles the wheel speed sensor sits inside or very close to the wheel bearing. A worn bearing can damage the sensor or disrupt its signal, triggering both the ABS and traction control lights.

“`html

ABS and Traction Lights On Together: Wheel Speed Sensor or ABS Module?

Expert advice from MnF Motors — Edmonton N18 | 4.9★ on Google

When your ABS warning light and traction control light come on at the same time, the most common cause is a faulty wheel speed sensor — not the ABS module. Both systems share the same sensor data, so one bad sensor knocks out both warning lights simultaneously. However, if live sensor data from a diagnostic scan shows all four sensors reading correctly, the fault points toward the ABS control module itself. Knowing which one it is before ordering parts saves time and money. Here is exactly how we tell them apart at MnF Motors.

Why Do Both Warning Lights Come On Together?

Your ABS (Anti-lock Braking System) and traction control system are not independent. They share the same wheel speed sensors, the same wiring loom, and — critically — the same ABS control module. The module reads wheel speed data continuously. If it receives a corrupt, absent, or wildly inconsistent signal from even one sensor, it disables both systems as a precaution and illuminates both dashboard lights.

This is actually good design. The car is telling you it has lost confidence in the data it needs to intervene safely during braking or wheel spin. What it cannot tell you directly is where in the chain the problem sits — and that is where proper Car Diagnostics comes in.

What Is a Wheel Speed Sensor and How Does It Fail?

A wheel speed sensor (WSS) sits at each wheel hub, reading a toothed reluctor ring as the wheel rotates. It sends a frequency signal to the ABS module — faster wheel, higher frequency. These sensors operate in a harsh environment: road grit, water, heat, and constant vibration. After enough years, the sensor tip corrodes, the wiring chafes, or the reluctor ring itself chips or rusts.

How Do We Identify a Faulty Wheel Speed Sensor?

Stored fault code: The ABS module logs a code pointing to a specific wheel — for example, C0035 (left front WSS), C0040 (right front WSS). This is the first and most direct clue.
Live data stream: We watch all four sensor readings in real time on the diagnostic tool while the car is driven slowly. A dead sensor shows zero mph while the others rise normally. An intermittent sensor drops in and out.
Physical inspection: We check the sensor body for cracks, the wiring connector for moisture or corrosion, and the reluctor ring for missing teeth or heavy rust buildup.

In well over 25 years of independent garage work, wheel speed sensors account for the large majority of combined ABS and traction light faults we see — especially on vehicles over five years old. It is the right place to start, and replacing a sensor is a fraction of the cost of a module.

When Does the ABS Module Become the Suspect?

If the diagnostic scan returns no wheel-specific fault codes, all four live sensor readings are clean and consistent, yet the lights remain on, attention shifts to the ABS module. The module can suffer internal circuit failure, power or earth supply issues, or — less commonly — software corruption. We also check:

Battery voltage and charging system health (a weak battery causes false module faults more often than most drivers realise)
Fuse and relay condition for the ABS circuit
Earth continuity at the module connector

Can the Module Be Repaired Rather Than Replaced?

On some vehicles, yes — specialist module repair is an option and can be significantly cheaper than a new unit. Whether that route is suitable depends on the module design and your car’s age. It is worth discussing before committing to a replacement. This kind of honest assessment is something our team prioritises on every job, whether it is a sensor swap or something more involved like an Engine Rebuild.

Should You Check for Active Warranties First?

If your car is newer or was recently serviced elsewhere, it is worth checking whether the repair might fall under a manufacturer or aftermarket warranty. Our Warranty Claims page walks through what we can help you with, so you are not paying for something that should already be covered.

Is an ABS Fault an MOT Failure?

Yes — since May 2018 an illuminated ABS warning light is a Major MOT