Why Won’t My Car Start? Common Causes
Clicking, slow cranking or nothing at all? What each symptom can point to, what you can safely check yourself, and when to stop turning the key.
The most common reason a car won’t start is a flat or failing battery, but a faulty starter motor, a fuel or ignition problem, or an immobiliser fault can all leave you stuck. The sound the car makes when you try to start it is your best clue, so listen before you do anything else.
Start with what you hear
Nothing at all, or dash lights that die
If the dashboard is dead or the lights fade as soon as you turn the key, suspect the battery first. A loose or corroded terminal can do the same thing, because power can’t get through even when the battery itself has charge left. With the car off, look at the terminals for white or green crust and check the clamps don’t move by hand.
Rapid clicking
A fast chatter of clicks usually means there is enough power to work the starter solenoid but not enough to turn the engine. That often points to a low battery. If a jump start gets you going but the car is flat again next time, the battery may not be holding charge, or the alternator may not be charging it.
One loud click
A single clunk with the dash lights staying bright can point to the starter motor or its solenoid. The battery is doing its job and the signal is getting through, but the engine isn’t turning.
Slow, laboured cranking
A weak battery is the usual suspect here, especially on the first cold morning of the year. Thick old oil and poor connections can add to it. Treat this as an early warning: it often gets worse quickly.
Engine spins normally but won’t fire
Now the battery and starter are probably fine and the fault lies elsewhere. It may be fuel not reaching the engine, an ignition problem on a petrol, glow plugs on a cold diesel, or a sensor telling the engine management system not to run. If the engine sounds unusually fast and free as it spins, stop trying. That can be a sign of a snapped cam belt, and repeated cranking won’t help.
Quick checks before you call anyone
- Check the fuel gauge. It sounds obvious, but gauges can read wrongly on a slope and a nearly empty tank catches people out.
- Look for a flashing key or padlock symbol on the dash. That can mean the immobiliser isn’t recognising the key. Try your spare, and if you have a keyless fob, try a new fob battery or follow the handbook’s method for a flat fob.
- Make sure an automatic is in Park, and that the clutch is fully down on a manual. Many cars won’t crank otherwise.
- Turn off the headlights, heater fan and radio so the battery has only one job to do.
- Try starting in short bursts of a few seconds, with a pause between them. Long cranking heats the starter and flattens what charge is left.
Jump starting safely
Follow the handbook, because some cars have dedicated jump points and some warn against being jump started in certain ways. Don’t attempt it if the battery is cracked, leaking or swollen, or if you can smell rotten eggs. Keep leads away from the fan and belts, and don’t lean over the battery while you connect them.
If you’re stuck on the road
Your safety comes before the car. The Highway Code says to get off the road if you can and use hazard lights if you’re causing an obstruction. On a motorway, get out on the left-hand side if it’s safe, stand behind the barrier and keep away from traffic. If you can’t get to safety, stay in the car with your seat belt on and hazards flashing, and call 999. Never use a warning triangle on a motorway.
How a mobile mechanic can help
A non-starter is one of the jobs that suits a mobile visit, because the car doesn’t need to be moved. On a driveway or in a car park we can test the battery, charging and starting circuits and, if the cause isn’t obvious, carry out mobile car diagnostics to read any stored fault codes. If it turns out to be the battery, see our car battery services. For a suspected starter fault, we also handle alternator and starter motor repairs, subject to the suitability of the job and location.
When you get in touch, tell us the make, model and year, and describe exactly what the car does when you turn the key. A short video or sound clip helps more than you might expect.