Car warning signs: what your car is telling you

Stop as soon as it is safe

• Temperature gauge in the red or a coolant warning: switch off and let the engine cool. Driving on risks head gasket damage.
• Flashing check engine light: usually a serious misfire that can damage the catalytic converter.
• Red brake warning light that stays on with the handbrake released, or a pedal that sinks: possible fluid loss.
• Oil pressure warning light: stop and switch off; low oil pressure can destroy an engine quickly.
• Smoke from under the bonnet or a strong burning smell.

Book in soon

• Squealing brakes or grinding: pads are wearing or worn through.
• Clunks over bumps: worn suspension bushes, links or joints.
• Pulling to one side: alignment, tyre pressure, or a sticking brake.
• Vibration at highway speed: wheel balance or tyre damage.
• Slow cranking on start-up: a tired battery or charging fault.
• A steady check engine light with the car driving normally.

What leaks usually mean

• Clear water under the passenger side on a hot day: normal air conditioning condensation.
• Green, pink or orange, sweet-smelling: coolant.
• Brown or black, slippery: engine oil.
• Red or brown, thinner than oil: transmission or power steering fluid.
• Clear to yellowish, slippery, near a wheel: possibly brake fluid. Treat this as urgent.

Smells worth noticing

• Sweet, syrupy: a coolant leak, sometimes into the cabin through the heater.
• Burning oil: oil leaking onto the hot exhaust.
• Burnt, acrid smell after hills or towing: an overheated clutch or brakes.
• Rotten eggs: often a fuel mixture or catalytic converter problem.
• Musty air from the vents: moisture in the air conditioning system.

Help us find it faster

Before you call, note when the symptom happens: cold or hot engine, at a particular speed, when braking, turning or going over bumps, and whether it is getting worse. If a warning light came on, avoid clearing it; the stored data helps the diagnosis.

Quick answers