A car that will not start is not one fault, it is about six different faults that happen to share a symptom. The quickest way to work out which one you have is to listen carefully to what happens when you turn the key or press the button, because each cause makes a distinctly different noise.
Start there, before anyone opens the bonnet.
Nothing at all: no lights, no sound
The dashboard stays dark and nothing responds.
- A completely flat battery is the usual answer. Try the headlights: if they are dead or very dim, that confirms it.
- Loose or corroded battery terminals produce exactly the same symptom as a flat battery. Look for a white or bluish crust, and check the clamps do not move when nudged.
- A blown main fuse or a failed earth strap is less common but possible.
- Something left on overnight — an interior light, a door not fully closed, a boot lid ajar — explains why an otherwise healthy battery is flat.
If a jump-start brings it straight back to life, the battery or the charging system is the thing to investigate, not the starter.
Rapid clicking, and the engine does not turn
A machine-gun clicking from the engine bay when you turn the key.
This is the classic sound of a battery with enough charge to operate the starter solenoid but not enough to turn the engine. The solenoid pulls in, the voltage collapses, it drops out, and it repeats several times a second. Treat it as a flat battery.
One loud click, and nothing else
A single solid clunk, then silence.
- The starter motor or its solenoid may have failed.
- The engine may be seized, though this is rare and usually follows a serious mechanical problem you would already know about.
- A poor connection at the starter can also do this.
This one usually needs a workshop.
The engine turns over but never fires
The starter spins the engine at a normal speed, but it never catches. The battery is fine; something else is missing. An engine needs fuel, spark and air in the right proportions at the right moment.
- No fuel. Check the gauge honestly, and remember gauges can read wrongly. If the car ran out, refilling a petrol car is usually enough; a diesel that has been run completely dry often needs bleeding before it will start, which is a workshop job on many modern cars.
- Immobiliser. If a key or padlock symbol is flashing on the dash, the car is not recognising the key. Try the spare key. A flat key battery, a damaged transponder or interference from other keys and fobs on the same ring are all common.
- Ignition or fuel delivery faults — coils, plugs, pump or filter — are workshop territory, but a car that cranked normally and then simply stopped firing is a useful thing to describe to a mechanic.
- Very cold or very damp conditions can make a marginal ignition system fail when it would otherwise cope. Diesels also need their glow plugs to work in the cold; if the coil symbol stays lit for a long time or the car struggles only on cold mornings, mention it.
The starter will not engage at all, but the electrics are fine
Full lights, no cranking, no click.
- Automatic cars need the selector properly in Park or Neutral. Move it firmly into Park, or try Neutral — a worn selector switch is a common and easily missed cause.
- Manual cars with a clutch switch need the clutch pedal pressed fully to the floor.
- The steering lock can bind against the key. Turn the steering wheel gently side to side while turning the key.
- A push-button car may not be reading the fob. Many have a defined position — often holding the fob against the start button or a marked spot on the column — for exactly this situation. The manual explains it.
What not to do
- Do not crank repeatedly in long bursts. Ten seconds at most, then wait.
- Do not spray anything flammable into the intake.
- Do not attempt to push-start or tow-start an automatic. It does not work and it can damage the transmission.
- If you smell fuel, stop and get help.
Worth noticing for later
If the car does start, pay attention to what happens next. A charging warning light, a slow crank, or a repeat failure the following morning all point at the battery and charging system rather than a one-off. Note anything unusual before, during or after — whether it had been standing, whether it was raining, whether it had run out of fuel — because that context genuinely helps whoever diagnoses it.
Your manual has the final word
Immobiliser procedures, emergency starting with a flat key fob, jump points and gear selector requirements are all specific to your car. Where this guide and your owner’s manual disagree, follow the manual.
