ABS warning light staying on? See common causes, how braking can be affected, why fault-code diagnosis matters and the potential MOT implications in the UK.
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An ABS warning usually means the anti-lock braking system has detected a fault. Conventional braking may still operate, but the anti-lock function and sometimes related stability systems may be unavailable.
A vehicle with an ABS fault may retain its normal hydraulic brakes, but anti-lock assistance may not work when a wheel is about to lock. If the red brake warning is also on, the pedal feels abnormal or braking performance has changed, treat the situation as more serious and stop driving.
ABS relies on accurate wheel-speed signals. Road debris, corrosion, damaged wiring, bearing problems and failed sensor elements can interrupt those signals. Reading the ABS module for fault codes and live wheel-speed data is usually more useful than replacing parts by guesswork.
An illuminated ABS malfunction indicator can be an MOT failure where the system is fitted and the warning indicates a fault. The exact inspection outcome depends on the vehicle and the defect recorded by the tester.
Diagnosis commonly starts with ABS fault codes, wheel-speed live data, sensor wiring and connectors, reluctor or encoder condition and wheel-bearing condition before moving on to hydraulic-unit or module faults.
Photograph the dashboard and AutoAid can help identify the symbol, ask follow-up questions and explain likely next steps.
Photograph the warning lightThe Highway Code advises drivers to understand dashboard warnings and not ignore signs that may indicate a serious developing fault. Your vehicle handbook remains the definitive source for the exact symbol and manufacturer-specific procedure.
AutoAid provides AI-assisted guidance only and never a guarantee. All faults, urgency ratings and prices are estimates — a physical inspection by a qualified mechanic may still be required.