Bulb Failure Warning Light

Can I keep driving?

What to do right now

1. 1Pull into a safe parking spot or layby when convenient to check your exterior lights.
2. 2Switch on your hazard warning lights and dipped beam headlights.
3. 3Walk around the car to see if any front, rear, or side lights are unlit.
4. 4Press the brake pedal against a wall or have a passenger check if the rear brake lights illuminate.

Likely causes

Most likely first.

1. Likely

   Blown standard filament bulb

   Tungsten filaments break naturally over time due to heat cycles and road vibration. This breaks the electrical circuit, which the car's lighting control module detects immediately.

2. Possible

   Incompatible aftermarket LED bulb fitted

   Standard LED bulbs consume far less electrical current than original incandescent bulbs. The car's computer interprets this low electrical draw as a burnt-out bulb.

3. Possible

   Corroded or loose bulb socket

   Water ingress or road salt can cause oxidation on the metal contacts inside the lamp cluster. This creates high resistance or an intermittent connection that triggers the warning.

4. Rare

   Damaged wiring or blown lighting fuse

   Wires that bend repeatedly, such as those inside the boot or tailgate rubber gaiter, can snap over time. A short circuit will also blow a dedicated lighting fuse and cut power entirely.

What you can check yourself

Park somewhere safe and level, engine off, before you start.

1. 1

   Full exterior lighting walkaround

   Turn the ignition on, switch on the dipped headlights and hazard lights, and walk around the vehicle. Look closely at every corner, including front sidelights, rear tail lights, and both rear number plate lamps.

2. 2

   Brake light check

   Reverse your car close to a wall, garage door, or shop window at dusk. Press the brake pedal and look in your rear-view mirror to verify that both main brake lights and the high-level centre light reflect clearly.

3. 3

   Inspect the suspect bulb

   Refer to your owner's handbook to access the bulb holder from inside the engine bay or boot lining. Remove the bulb and check if the glass is blackened or if the delicate wire filament inside is broken.

4. 4

   Check the socket for moisture and corrosion

   Look inside the empty bulb holder for green or white powdery corrosion and signs of water droplets. Clean any light surface corrosion with electrical contact cleaner before inserting a fresh bulb.

Typical prices in Ireland (€) and the UK (£), from an independent garage up to a main dealer. Prices vary mostly between replacing a cheap, accessible filament bulb yourself and having a garage replace an entire sealed modern LED headlamp cluster.

When to go to a garage

• The warning light remains illuminated on your dashboard even after you have installed the correct new bulb.
• Multiple lights stop working at the same time, pointing to a blown fuse, body control module fault, or wiring harness break.
• Accessing the bulb requires taking off the front bumper or wheel arch liner and you do not have the tools to do so safely.
• The light housing shows visible water pooling or severe corrosion inside the electrical plug connector.

Questions drivers ask

Test rules here are for the National Car Test in Ireland (NCT) and the MOT in the UK. Elsewhere, check the regulations of your own country or state before going for a vehicle test.