Why does my car stall?
A car that stalls at idle, at traffic lights, or when pulling away usually has an idle control problem — the engine cannot maintain the minimum revs needed to keep running. Common causes are a dirty throttle body, faulty idle air control valve, or vacuum leak. On manual cars, stalling when pulling away is usually driver technique — but if it happens when the car is already moving, it is a mechanical issue.
Likely causes
Dirty or faulty idle air control valve
Controls air bypass at idle — failure causes unstable or low idle that drops to stall
Dirty throttle body
Carbon buildup restricts airflow at idle — cleaning often resolves the issue
Vacuum leak
Unmetered air causes lean idle — engine cannot maintain stable revs
Faulty crankshaft position sensor
Intermittent signal loss causes sudden engine cutout
Fuel delivery issue
Weak fuel pump or clogged injector causes lean misfire at low load
Repairs you may need
Typical cost range: £40–£350 — Throttle body cleaning: £60–120. IAC valve: £80–200. Fuel filter: £50–150. Crank sensor: £80–200.
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