Engine Cranks But Won’t Start
If the starter turns the engine normally but it never fires, the engine is missing fuel, spark, a crankshaft signal or permission from the immobiliser.
Normal risk
No danger while driving, but avoid long cranking; it drains the battery and can overheat the starter.
Short answer · Why does my engine crank but not start?
The battery and starter are working, so the problem is elsewhere. Check for an immobiliser or key warning first, then fuel: is there enough, and can you hear the fuel pump hum for a moment when switching on? A failed crankshaft sensor or a timing belt failure also cause this. Codes and a fuel pressure test narrow it down.
Safe checks you can do
- Check the dashboardA flashing key or immobiliser symbol points to the key.
- Listen for the fuel pumpWith the ignition on, many cars hum briefly from the rear.
- Check the fuel levelA faulty gauge can hide an empty tank.
Questions that narrow it down
- Is the immobiliser light flashing?Try the spare key.
- Does the rev counter move while cranking?No movement can mean a crankshaft sensor fault.
- Was the timing belt due?A snapped belt causes a no-start.
Possible causes
Listed without ranking. Use the questions above to see which ones fit your car.
- Immobiliser not recognising the keyKey battery or chip.
- No fuel or no fuel pressureEmpty tank, pump or relay.
- Crankshaft sensorNo speed signal.
- Broken timing beltEngine cranks unusually fast.
- Flooded engineToo much fuel after short starts.
Questions about Engine Cranks But Won’t Start
How long should I crank?
No more than about 10 seconds at a time, with pauses between attempts.
Can a dirty fuel filter cause it?
A completely blocked filter can, especially on diesels.