Guides
Car Won't Start: Finding the Cause by Symptom
The key question is: what happens when you try to start it? The answer already narrows down the cause a lot.
First question: does the starter motor turn?
| What you hear | What it usually means |
|---|---|
| Nothing, no lights on the dashboard | Flat battery or a loose terminal |
| A single click, nothing else | Battery too weak, starter motor, or a connection |
| Starter turns slowly | Weak battery, often in cold weather |
| Starter turns quickly, engine doesn't start | Fuel, ignition, the glow system on a diesel, or sensors |
| Starter doesn't respond, dashboard lights up | Immobiliser, key, starter, or start-permission system |
In most cases, it's a weak or flat battery. Next come the starter motor and the fuel supply.
Starter motor doesn't turn
- Battery: lights, radio or central locking work poorly or not at all. Jump-starting is the first thing to try, see Jump-starting and a flat battery.
- Terminals: loose or corroded terminals interrupt the current. If you can safely reach them, check them.
- Automatic: is the selector in P or N? Press the brake pedal while starting.
- Immobiliser: if the key has a faulty transponder, or the vehicle doesn't recognise it, the system refuses to start. Try the spare key. With keyless-go, a weak key-fob battery can be the cause.
Starter turns, engine doesn't start
- Fuel: tank empty? Wrong fuel? Then stop trying, see Wrong fuel. A faulty fuel pump or a blocked filter also cuts the supply.
- Diesel engine in winter: faulty glow plugs often prevent a cold start, while the warm engine still starts.
- Ignition or sensor: the ignition system, crankshaft sensor, or control unit. This can only be checked at a garage.
- Marten damage: chewed-through cables or hoses can prevent starting.
What not to do
- Don't crank it for minutes on end. That drains the battery and can overload the starter motor. Pause a few seconds to a few minutes between attempts.
- Don't spray starter fluid into the intake unless you know exactly what you're doing.
- Don't push-start if your vehicle has an automatic transmission, a catalytic converter, or sensitive electronics. Many modern cars aren't designed for it.
When you should call for help
If jump-starting doesn't help, warning lights are on (see Warning lights in your car), there's smoke from the engine bay, or you're somewhere dangerous. The vehicle is then taken to a garage on a flatbed. For hybrids and electric cars, that's the safe route anyway, see Towing an electric car.
Frequently Asked Questions
My car just clicks. Is the starter motor broken?
Usually the battery is too weak. Only if jump-starting doesn't help does the starter motor become a likely candidate.
Why does my diesel only fail to start in cold weather?
On diesel engines, faulty glow plugs can prevent a cold start. A warm engine often still starts.
Am I allowed to push-start my car?
On many modern vehicles, especially automatics, this isn't designed to work. Read the owner's manual.
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