🌡️ Temperature Warning Light: Never Ignore This One

The temperature gauge or warning light is one of the few dashboard warnings that demands you stop the car immediately. Driving an overheating engine for even a few extra minutes can cause damage that costs thousands to repair — or writes the car off.

What to do right now

1. Turn off the air conditioning (it adds load to the engine) but turn the heater to full heat — this draws heat away from the engine into the cabin.
2. Pull over and turn the engine off. Don't switch to neutral and coast — the engine is still running.
3. Wait at least 30 minutes before touching anything under the bonnet. The cooling system is pressurised when hot.
4. Once cool, check the coolant reservoir (a translucent plastic tank, usually with a min/max line). If it's empty or very low, that's your immediate cause.
5. Do not top up with plain water if you can avoid it — use the correct coolant mixture, or at minimum distilled water as a temporary fix.
6. If the reservoir fills but the car overheats again quickly, do not keep driving. Call recovery.

Common causes of overheating

• Low coolant — a slow leak from a hose, radiator, or the water pump
• Thermostat failure — the thermostat sticks closed and coolant can't circulate
• Cooling fan failure — the fan that pulls air through the radiator at low speed stops working
• Blocked radiator — debris or scale reducing cooling capacity
• Head gasket failure — the most serious cause; coolant leaks into the combustion chamber

Signs of a blown head gasket

A blown head gasket is expensive (£1,000–£2,000+ on many cars). Warning signs: white smoke from the exhaust, a sweet smell from the engine, milky or foamy oil on the dipstick, coolant level dropping with no visible external leak. If you see any of these alongside overheating, the car needs professional attention before it's driven again.