If the starter turns but the engine does not start, the battery and cranking are fine: fuel, spark (or glow plugs), the speed signal or compression is missing. It is solved by process of elimination.
Quick check, in order
- Immobiliser warning light flashing? Try the second key and check the remote battery.
- Fuel: empty tank, or no pump hum with the ignition on.
- Battery: does it crank slowly or click? A weak start turns little and badly.
- Glow plugs (diesel): in winter, if they do not preheat, starting is hard.
- Crankshaft sensor: the starter turns but the rev counter stays at zero.
Most frequent causes
| Cause | How to recognise it | What to do |
|---|---|---|
| Crankshaft / position sensor | Rev counter still, sudden stalling | Replace the sensor |
| Fuel pump or relay | No pump noise with ignition on | Check relay and pump |
| Clogged fuel filter | Starting takes longer and longer | Replace the filter |
| Worn glow plugs (diesel) | Will not start when cold | Replace and check the glow plug unit |
| Spark plugs/coils (petrol) | Smell of petrol, misfire symptoms | Replace |
| Immobiliser | Security light flashes | Read in diagnosis, reprogram the key |
| Broken timing belt | Starter turns too freely, no compression | Mechanical check |
What not to do
- Do not crank for long: it drains the battery and overheats the starter
- Do not spray "easy start" on a diesel: it can damage the engine
- Do not disconnect the battery at random: you lose adaptations and codes useful for diagnosis
How MasterTuning helps
We read the real values of the control unit, not just the code: that is the difference between finding the faulty component and replacing parts by trial and error. After the repair we clear the error and check that it does not come back. Find the nearest centre or contact us.
Car will not start and you do not know why? Book a diagnosis at the nearest MasterTuning centre.
Frequently asked questions
Why does the starter turn but the car does not start?
Fuel, spark or glow plugs, the speed signal or compression is missing: battery and starting are fine.
Can it be the timing?
Yes, if the belt or chain has broken: the starter turns too freely and there is no compression.
Can it be the alarm?
Yes: if the immobiliser does not recognise the key the engine turns but does not start.
How much does it cost to fix?
It depends on the cause: from the filter (€30-100) to the crankshaft sensor (€60-200) up to mechanical work.
