Normal braking is generally unaffected when only the ABS light is on, since ABS is an assistance system rather than the core brake system. However, the anti-lock and often the stability control systems will be disabled, meaning wheels can lock up under hard or emergency braking, particularly on wet or slippery roads.
ABS (anti-lock braking system) prevents wheels from locking up under hard braking, helping maintain steering control. When the ABS light comes on by itself — without an accompanying brake warning light — your normal brakes still work, but this specific assistance feature has been disabled due to a detected fault.
A faulty wheel speed sensor is the most common cause, often due to dirt, debris, or damage to the sensor or its wiring. Less commonly, a fault within the ABS control module or hydraulic pump itself can trigger the light.
If the ABS light is accompanied by the main brake warning light, this suggests a more significant issue potentially affecting the core braking system itself, not just the ABS assistance feature, and should be treated with more urgency.
Drive more cautiously than usual, particularly in wet, icy, or otherwise slippery conditions, since you won't have the benefit of ABS or stability control to help maintain control under hard braking. Leave extra following distance and avoid harsh braking where possible until it's fixed.
Yes — an illuminated ABS warning light will fail an MOT in the UK, since it indicates a safety-related system isn't functioning as intended, even though your core brakes still work normally in daily driving.
| Likely Cause | Typical UK Cost |
|---|---|
| Wheel speed sensor replacement | £70 – £200 |
| ABS control module repair/replacement | £250 – £700 |
Yes, normal braking is unaffected — ABS is an assistance feature that prevents wheel lock-up under hard braking, and it's this specific function that's disabled, not the core brakes.
It's generally not immediately dangerous for normal driving, but you'll lack ABS and often stability control assistance under hard or emergency braking, so extra caution is warranted, especially in poor weather.
A faulty or dirty wheel speed sensor is the most common cause, though a fault within the ABS control module itself is also possible, particularly on older vehicles.
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Get My Free Fault ScanLast reviewed 2026-09-08 by the MotorLoom editorial team.