When a car refuses to start, what it does when you turn the key tells you most of what you need to know. Silence and dead dashboard lights point to the battery or its connections. A rapid clicking points to a battery that is too weak to turn the starter. An engine that cranks normally but never fires points to fuel, air or ignition. Run through the checks below before you call for help, because a surprising number of no-start calls end with a loose terminal, a car left in the wrong gear, or an empty tank.
Start by listening and looking
| What happens | Most likely cause | What to try |
|---|---|---|
| Nothing at all: no lights, no sound | Flat battery or loose, corroded terminals | Check headlights and interior light; wiggle and tighten the terminals; try a jump-start |
| Fast clicking, dim lights | Weak battery | Jump-start or charge; have the battery tested afterwards |
| Single loud click, lights stay bright | Starter motor or solenoid fault | Often needs a mechanic; a jump-start will not help |
| Engine cranks but does not start | No fuel, a fuel delivery fault, or an ignition or injection problem | Check the fuel gauge; listen for the fuel pump hum; see the diesel notes below |
| Starts and dies at once | Immobiliser, air intake or fuel fault | Look for a key or lock warning light; try the spare key |
| Dashboard shows a key or lock symbol | Immobiliser not recognising the key | Try the spare key; replace the key fob battery |
The simple checks that fix more than you would think
- Gear and pedals. An automatic must be in P or N. A manual often needs the clutch pedal fully pressed. Some cars also need the brake pedal pressed for push-button start.
- Steering lock. If the key will not turn, wiggle the steering wheel gently while turning the key.
- Key fob battery. A flat fob battery can stop a push-button car from starting. Many fobs have a backup slot for holding the key near a marked spot on the steering column or console; check the handbook.
- Fuel. Do not trust a gauge that has been showing low for days, since a car parked on a slope can also read differently from one on level ground.
- Terminals. A loose clamp or white and green corrosion can stop a good battery from delivering power. If safe to do so, tighten and clean them.
- Lights and accessories. Switch off the air conditioning, headlights and audio before cranking, since they take power from a weak battery.
Jump-starting safely
A jump-start is the standard remedy for a battery that has simply run flat. It requires a second car with a healthy 12-volt battery, a set of jump leads in good condition, and a few minutes of care.
- Park the donor car close but not touching. Switch both cars off and put them in park or neutral with the handbrake on.
- Connect one red clamp to the positive terminal of the flat battery.
- Connect the other red clamp to the positive terminal of the donor battery.
- Connect one black clamp to the negative terminal of the donor battery.
- Connect the final black clamp to a clean, unpainted metal part of the engine or body of the flat car, away from the battery.
- Start the donor car and let it run for a few minutes. Then start the flat car.
- Once it runs, remove the clamps in the reverse order, and keep the engine running or drive for a while so the alternator can recharge.
Do not jump-start a battery that is cracked, swollen or leaking, and keep sparks and flames away because batteries can release flammable gas. Check the handbook of both cars, since some modern models have specific jump points. If a car dies again soon after a jump, the battery or alternator is probably failing and needs testing. The monsoon checklist and the trip checklist both include battery checks.
Notes for diesel cars
Diesel engines have extra reasons for failing to start. Running the tank completely dry can let air into the fuel system, and the engine may then crank without firing even after you add fuel. Many modern cars can clear this by cranking in short bursts, some have a manual primer, and some need a mechanic to bleed the system. Worn glow plugs or a clogged fuel filter can also cause hard starting, particularly on cool mornings in the hills.
Electric and hybrid cars
Electric cars also have a 12-volt battery that runs the electronics and contactors, and when it fails, the car may appear completely dead even with a charged traction battery. Jump-starting procedures for these cars are specific, so check the handbook before attaching any clamps. If in doubt, call the roadside service listed for your car.
When to call for help
If the quick checks do not help, or if you see smoke, smell burning, or are in an unsafe spot, stop trying and call. Do not keep cranking for long periods, which can overheat the starter motor and drain the battery further. A mobile mechanic can fix many battery, terminal and fuel-related faults on site, but a faulty starter, a failed fuel pump or an electronic fault usually means a tow. The towing guide sets out what to ask before a truck arrives, and the guide to choosing a garage helps with the next step.
Frequently Asked Questions
Why does my car click but not start?
Rapid clicking usually means the battery is too weak to turn the starter. A single loud click with bright lights can mean a starter or solenoid fault. A jump-start helps in the first case but not the second.
Can I push-start my car?
Some manual cars can be push-started in second gear, but many modern cars should not be, and automatics cannot. Check the handbook, and use jump leads where you can.
How long should I leave the donor car running?
A few minutes before trying the flat car is usually enough. After the car starts, drive or idle for a while so the alternator can recharge the battery.
My diesel ran out of fuel. Will it restart after refuelling?
Sometimes not at once. Air can enter the fuel system and prevent starting. Add fuel, then try short cranking bursts. If it still will not start, the system may need bleeding by a mechanic.
How do I know if the battery or the alternator is at fault?
If a jump-start works but the car dies soon after, or the battery warning light stays on while driving, the alternator is a suspect. A garage can test both in a few minutes.