Last checked against official sources on 2 October 2026.
This guide is general information, not legal, tax, financial or mechanical advice. Rules, rates and fees change, so confirm the details with the official sources listed at the end before you act. CarQnA is not affiliated with any of them.
Dashboard warning lights meaning comes down to colour: red means stop as soon as it is safe, amber means get it checked soon, and green or blue is information only.
Red lights: stop safely
- Oil pressure: switch off and check the level. If the light stays on, have the car recovered.
- Engine temperature: stop, switch off, never open a hot coolant cap.
- Brake (! in a circle): check the handbrake. If it is off, suspect low brake fluid.
- Battery: charging fault. Drive straight to a garage before the car stops.
- Electric or hybrid high-voltage warning: stop safely, never touch high-voltage parts.
Amber lights: book it in
- Engine management, steady: book a diagnostic check.
- Engine management, flashing: usually a misfire. Slow down and get it seen as soon as possible.
- ABS: normal brakes work, but wheels could lock in a hard stop.
- Tyre pressure: check all four for a slow puncture, then reset.
- Airbag: may not deploy. Get it checked promptly.
- DPF (diesel): try a steady motorway run. If it stays on, see a garage.
Warning lights and the NCT
- The fault behind a light can fail the NCT if it is in a tested system such as the brakes.
- Clearing the light fixes nothing: get it diagnosed and repaired.
- Any garage, or an inexpensive OBD reader, can read the fault code.
Common questions
Can I drive with the engine management light on?
If it is steady and the car drives normally, drive carefully to a garage, but if it flashes get it checked as soon as possible.
Will a warning light fail the NCT?
The fault behind it can, if it is in a tested system such as the brakes.