Car lighting: checks and bulbs

Lighting in good condition is essential to see and be seen, and to pass the MOT. Here are the checks to do and the basics of bulb replacement.

Points to check

Dipped and main beam headlights: operation, aim (height), lens cleanliness. Side lights. Indicators front, rear and side. Brake lights and number plate light. Fog lights (front and rear) if fitted. Lens condition: yellowed or cloudy lenses reduce effectiveness; polishing can help, replacement is the lasting solution.

When to check

At each service or oil change, and before a long trip or night drive. If a message or warning light appears on the dashboard (bulb failure on some vehicles). Before the MOT: a faulty light can result in a defect.

Replacing a bulb

Consult the handbook for the bulb type (H7, H4, W5W, etc.) and access (often from behind the lamp, sometimes battery or air filter removal). Disconnect the lights before opening. Do not touch the glass of halogen bulbs with bare hands (grease = overheating and failure). Check operation after replacement. For LED or xenon, replacement may be more delicate or reserved for the garage.

Safety

Driving with a faulty light is dangerous and can be penalised. If a light fails while driving, reduce speed, switch on hazard lights if necessary and replace the bulb or have it repaired as soon as possible.

My Auto Check-up helps you track your vehicle’s symptoms to anticipate maintenance and safety.