Listen first: what happens when you turn the key?
Nothing at all, or dashboard lights are dim or off. The battery is most likely flat, or a battery terminal is loose or corroded. Check whether interior lights and headlights come on normally.
A rapid clicking sound. The battery has enough power to operate the starter solenoid but not to turn the engine. This is classic weak-battery behaviour, though a poor connection can cause it too.
A single click, then nothing. The battery may be fine but the starter motor, its solenoid or the wiring to it is not doing its job.
The engine cranks normally but won’t fire. The battery and starter are working; the problem is more likely fuel (empty tank, fuel pump, blocked filter), ignition, a sensor fault, or the immobiliser not recognising the key.
It cranks slowly, then maybe starts. A tired battery, a charging problem or corroded connections are the usual suspects — especially if it is worse on cold mornings or after the car has stood for a few days.
Common causes
- Weak or flat battery — the most common cause, particularly after short trips, long periods parked or lights left on.
- Charging system fault — a failing alternator means the battery is never properly recharged.
- Starter motor or solenoid — wear inside the starter, or a poor connection to it.
- Fuel supply — running very low, a failing fuel pump or a blocked filter.
- Immobiliser or key — a key the car no longer recognises, or a flat key-fob battery on some push-button-start vehicles.
- Sensors and electrics — for example a crankshaft position sensor fault, a blown fuse or a failed relay.
What you can do right now
- Check the lights and dashboard — dim or no lights point to the battery.
- Make sure the gear selector is in P (automatic) or the clutch is fully pressed (manual) — some cars will not crank otherwise.
- On push-button-start cars, hold the key fob close to the start button in case its battery is weak.
- Check for obvious loose or corroded battery terminals — only if it is safe to do so.
- Try a careful jump-start if you suspect the battery.
- If the engine cranks but won’t start, avoid cranking for long periods — it drains the battery and can overheat the starter.
When to get a professional inspection
If the car needs repeated jump-starts, won’t start even with a good battery, shows a security or check engine light, or you notice a burning smell, have it inspected. Guessing and replacing parts — especially batteries — often costs more than a proper test.
We test the battery, charging system, starter circuit and relevant sensors, read the fault codes, and explain what we find with an estimate before any repair.
