How it works
Enter your car
Describe the problem
Lubock analyses the causes and guides you through the checks
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Likely causes
- 1Dead or weak battery
- 2Starter motor
- 3Alternator
Checks to perform
- Check that the battery terminals are clean and tight.
- Turn on the headlights: if very dim, the battery is dead — try jump leads.
- Make sure there's fuel in the tank.
- Try the second key to rule out the immobilizer.
When a car won't start the problem is almost always electrical or starting-related, less often fuel. In most cases it's fixed with a few checks and no workshop visit. Here are the most common causes in order of likelihood and the checks you can do yourself.
Dead or weak battery
The most frequent cause. If you only hear a click or the dashboard lights up faintly (or stays dark) when you turn the key, the battery lacks the energy to run the starter. Check the terminals (clean and tight) and try jump leads from another car.
Starter motor
If the battery is charged but you hear only a sharp click each try, the starter may be stuck or worn. A light tap on its body (by a mechanic) sometimes frees worn brushes, but it points to replacement.
Alternator
If the battery keeps draining even after charging, the alternator may not be charging it while driving. Often preceded by warning lights flickering or headlights dimming at idle.
Fuel or clogged filter
Empty tank (the gauge can also lie) or a very clogged fuel filter. In diesels, air in the system or worn glow plugs prevent cold starts.
Immobilizer or key not recognized
If the immobilizer light flashes, the car doesn't recognize the key (damaged transponder chip, unprogrammed spare, or dead key battery in smart keys). Try the second key.
Fuses or crankshaft sensor
A blown starter-circuit fuse or a faulty crankshaft position sensor can prevent starting. Less common but easy for a workshop to check.
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