Engine Overheating: What to Do?

Immediately, while still driving

1. Switch off the air conditioning. It puts extra strain on the engine.
2. Turn the heating to its highest setting. It's unpleasant, but it draws heat out of the cooling circuit.
3. Ease off the accelerator, don't rev the engine, and find a safe place to stop.
4. As soon as the gauge is in the red zone or a warning appears, switch off the engine.

After stopping

• Switch on hazard lights, turn off the engine, put on a hi-vis vest.
• Open the bonnet so the heat can escape. Keep your distance from any steam.
• Don't open the radiator cap. The cooling system is under pressure, and hot coolant can spray out. Wait around fifteen minutes for everything to cool down.
• Then check the coolant and oil level, and look for leaks.

How to recognise overheating

• The coolant temperature rises sharply, or the warning light comes on
• The fan runs continuously
• Steam or smoke from under the bonnet
• A sweet smell of coolant
• The engine loses power

Common causes

The most common causes are a faulty thermostat that doesn't open the cooling circuit, a failed water pump, a blocked radiator, or a faulty radiator fan. Too little coolant due to a leak can also be the reason.

Top up coolant: yes or no?

If you're carrying coolant and the engine has cooled down, you can top it up. But afterwards only drive as far as the nearest garage, and watch the gauge. Topping up doesn't fix the cause. If the coolant disappears again immediately, there's a leak.

Keep driving, or get towed?

An overheated engine can suffer expensive damage, for example to the cylinder-head gasket. So: if the temperature rises again after cooling down and topping up, don't keep driving. Call a towing service. The vehicle is taken to a garage on a flatbed. If instead the engine simply cuts out while driving, see Engine cutting out while driving.

On the motorway, also remember: get behind the crash barrier, put on the hi-vis vest, then make phone calls, see Breaking down on the motorway. What the individual symbols mean is covered in our guide Warning lights in your car.