Stop drivingred light
Coolant Temperature Warning
Engine overheating — pull over before it cracks the head.
What it means
A red thermometer dipped in water. The engine has exceeded its safe operating temperature. Driving on can warp the cylinder head, blow the head gasket, or seize the engine — turning a £20 coolant top-up into a £2,000+ bill.
What to do
- 1Pull over safely and switch the engine off. Open the bonnet to let heat escape.
- 2DO NOT open the coolant cap while hot — pressurised steam can scald.
- 3After 20–30 minutes, check the expansion tank level. Top up if low, then drive carefully to a garage.
- 4If it overheats again, call recovery.
Likely causes
- •Low coolant (often from a leaky hose or expansion tank)
- •Failed thermostat stuck shut
- •Faulty water pump
- •Blocked radiator or failed cooling fan
- •Head gasket failure
Rough UK cost
Top-up: £8–£20. Thermostat: £100–£250. Water pump: £250–£600. Head gasket: £800–£2,500.
Prices are a guide only — always get a written quote before any work.
Heads up: Carautonomy is for general guidance only. If your car is behaving oddly or any red light is on, get it inspected by a qualified mechanic.