Car Overheating in Traffic? Causes and What To Do

4 June 2026 · 6 min read

What to do the moment it overheats

If the temperature gauge climbs into the red or a warning light comes on, do not keep driving. Pull over safely, switch the engine off, and let it cool. Continuing to drive an overheating engine risks a warped head or a blown head gasket — a far bigger bill than the original fault.

Never open the coolant cap while the engine is hot, as the system is under pressure and can spray scalding coolant. Once cool, you can check the coolant level, but the safest step is to have the car recovered and diagnosed.

Why it overheats in traffic but not at speed

A very common pattern is a car that runs fine on the move but heats up in slow, stop-start traffic. At speed, air is forced through the radiator naturally; in traffic that airflow depends on the electric cooling fan. If the fan is not running, the engine overheats exactly when it is sitting still.

So a car that overheats in traffic but cools down as soon as it gets moving very often has a cooling fan fault — a failed fan motor, a faulty relay, or a temperature sensor not switching it on. It is a specific, diagnosable cause.

Other common causes

Overheating can also come from a low coolant level or a leak, a stuck thermostat that stops coolant circulating, a failing water pump, a blocked or leaking radiator, or a head gasket fault letting combustion gases into the coolant. Each has its own signs and its own fix.

Because there are several possible causes, we test rather than guess — pressure-testing the system, checking the fan and thermostat operation, and running a combustion gas test on the coolant where a head gasket is suspected.

Overheating diagnosis in Bilston

If your car is running hot, get it checked before it does lasting damage. We will find the real cause, explain it clearly, and give you a costed recommendation before any work is agreed.

Call Wolverhampton Auto Care on 01902 494948 or book online. We are on Hare Street, Bilston, WV14 7JW, serving Darlaston, Willenhall, Wednesbury and Wolverhampton.

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