Clicking, or nothing at all
A rapid clicking or no sound with dim dash lights usually points to a flat or failing battery, or a poor battery connection. Check the terminals are tight and free of white or green corrosion. If a jump start gets it going, the battery or the charging system still needs testing, because a battery that went flat once for no clear reason often does it again.
Cranks but will not fire
If the engine turns over at normal speed but does not start, the cause is more likely fuel, ignition or an immobiliser fault. Check the fuel gauge, watch for a flashing key or security light on the dash, and try the spare key. Repeated long cranking can flatten the battery, so stop after a few attempts.
Starts then dies
An engine that starts and immediately stalls can be an immobiliser not recognising the key, a fuel delivery problem or an idle control fault. Note whether it happens hot, cold or every time.
What to tell the mechanic
Describe exactly what happens when you turn the key, whether the dash lights come on, any warning lights, the age of the battery if you know it, and whether the car is at home, at work or on the road. A mobile mechanic or auto electrician can often diagnose a no-start where the car is.
Safe to drive?
If it will not start, it is not going anywhere. If a jump start works, drive it straight to be tested rather than relying on it restarting.
General guidance only, not a diagnosis. If in doubt, do not drive it and have it inspected. In an emergency, call 111.
Who can help
Get quotes for car battery replacement near you
Questions
Can a new battery still be the problem?
Yes, if it was never charging properly. An alternator fault or a parasitic drain will flatten a new battery. Ask for a charging system test.
Should I keep trying to start it?
No. A few attempts is enough. Long cranking flattens the battery and can overheat the starter.