Car won't start: what to do and what it means
The fastest way to diagnose a no-start is to identify exactly what happens when you turn the key or press the start button. Each symptom points to a different cause. Find yours below.
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Symptom
Single loud click when turning the key or pressing the button
Most likely cause: Faulty starter motor solenoid
A single loud click followed by nothing usually points to the starter motor solenoid energising but the motor itself not turning. The solenoid is the electrical switch that engages the starter motor. It can fail on its own without the rest of the starter being worn out. This is distinct from a flat battery, which typically produces rapid clicking rather than a single click.
What to try first:
- 1Check the battery terminal connections: if they are loose or corroded, tighten and clean them. A poor battery connection can cause the solenoid to click without enough current to spin the motor.
- 2Try rocking the car gently in gear (manual) or putting it in park then back to neutral (automatic) and retrying. In rare cases a starter motor sticks and light movement unsticks it.
- 3If the battery connections are fine and the single click persists, the starter motor or solenoid needs replacement.
Typical repair cost: Starter motor replacement: £150 to £350 at an independent garage.
Symptom
Rapid clicking noise (like a machine gun) when turning the key
Most likely cause: Flat or low battery
Rapid clicking is one of the most common causes of a no-start. It means the battery has enough charge to engage the starter solenoid repeatedly, but not enough to actually spin the starter motor. Each click is a solenoid engagement attempt. A battery that is borderline may start the car on a warm day but fail on a cold morning.
What to try first:
- 1Jump start the car using jump leads and a running vehicle or a portable jump starter pack. If the car starts and runs normally, the battery needs testing.
- 2Once running, drive for at least 30 minutes to let the alternator recharge the battery. Avoid short trips for the next few days.
- 3Have the battery tested with a load tester at a garage or parts shop (many will test for free). A battery over five years old that is struggling should be replaced proactively.
Typical repair cost: Battery replacement: £80 to £180 including fitting, depending on the battery specification.
Symptom
No sound at all when turning the key (dead silence)
Most likely cause: Completely flat battery, blown fuse, or broken ignition circuit
Absolute silence when turning the key suggests either no electrical power reaching the starter circuit at all, or a severe electrical fault. This is different from clicking, which at least indicates some battery power. Possible causes include a completely dead battery (too flat even to click), a blown starter fuse, a faulty immobiliser preventing the circuit from completing, or in rare cases a broken ignition switch.
What to try first:
- 1Check if any interior lights, the radio, or dashboard lights come on at all. If there is truly no electrical response, the battery is likely completely dead or there is a broken connection.
- 2Attempt a jump start. If there is still no response after a jump start attempt with good connections, a fuse or relay may be the issue.
- 3Check the main fuse box for any blown fuses related to the starter or ignition circuit. The owner's manual or fuse box cover lists fuse locations.
- 4If the car has a working key fob with a dead battery, the immobiliser may prevent starting. Try holding the key fob against the start button, or replacing the key fob battery.
Typical repair cost: Fuse replacement: under £10. Battery: £80 to £180. Ignition switch: £150 to £350.
Symptom
Engine cranks (turns over) but will not fire
Most likely cause: Fuel delivery, spark, or immobiliser problem
If the starter motor turns the engine over normally but it will not actually start and run, the battery and starter are working. The fault lies elsewhere: the engine is not getting sufficient fuel, is not getting a spark, or is prevented from starting by the immobiliser. Petrol engines need fuel, air, and a spark. Diesel engines need fuel, air, and compression (no spark plug). Missing any one prevents the engine from firing.
What to try first:
- 1Check the fuel gauge. Running out of fuel is more common than it seems and causes exactly this symptom.
- 2For petrol cars: listen for a quiet hum from the fuel tank for two to three seconds when you first turn the key to the 'on' position (before cranking). This is the fuel pump priming. No hum suggests a failed fuel pump.
- 3Check if any security or immobiliser warning lights are flashing on the dashboard. If the immobiliser has not recognised the key, the engine will crank but not start.
- 4If the car has not been used for several weeks, a stale fuel or dry injector issue is possible.
Typical repair cost: Fuel pump replacement: £250 to £600. Spark plug replacement: £80 to £200. Injector diagnostic and clean: £150 to £400.
Symptom
Car starts but immediately cuts out
Most likely cause: Immobiliser fault, fuel pressure issue, or idle control problem
A car that briefly fires and then immediately dies often has the immobiliser cutting the fuel supply after a second or two because it has not fully authenticated the key. It can also indicate a fuel pressure issue where the pump can supply enough fuel to start but not sustain idle, or a faulty idle air control valve causing the engine to stall before it has warmed up.
What to try first:
- 1Try the spare key if you have one. If the spare key starts the car normally, the primary key has a transponder fault.
- 2Hold the key fob close to the ignition barrel and try again, as a weak transponder signal can cause partial authentication.
- 3If both keys cause the same behaviour, get the car diagnosed. An immobiliser reset or fuel system pressure test will identify the cause.
Typical repair cost: Key reprogramming: £80 to £200. Fuel pressure regulator: £150 to £350. Idle control valve: £100 to £250.
Symptom
Car will not start in cold weather
Most likely cause: Weak battery, thickened engine oil, or diesel gelling
Cold weather amplifies existing marginal conditions. A battery at 0°C has roughly 50% of its warm-weather capacity. Engine oil becomes thicker, increasing resistance for the starter motor. Diesel fuel can partially gel in very cold temperatures if it has not been formulated for winter use. A car that just about starts in summer may reliably fail in winter.
What to try first:
- 1Turn off all electrical loads (heated screens, radio, blower) before attempting to start in cold weather, to give the starter motor maximum available current.
- 2Try the ignition twice: turn to position II (accessories on) for a few seconds, then try starting. This allows the fuel pump to prime fully.
- 3For diesels that have been standing outside in sub-zero temperatures: wait ten minutes with the ignition on (position II) to warm the glow plugs before cranking.
- 4Have the battery load-tested. A battery under five years old failing in winter was likely already marginal.
Typical repair cost: Battery replacement: £80 to £180. Winter diesel additive: £10 to £25 preventive.
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Frequently asked questions
What is the most common reason a car won't start?
A flat or failing battery is by far the most common reason a car won't start. The tell-tale sign is rapid clicking when you turn the key, or a slow cranking speed. A battery over five years old is a likely candidate. Jump starting and then getting the battery properly load-tested is the first step. Starter motor failure (single click or no cranking) and fuel delivery problems (cranks but won't fire) are the next most common causes.
Can I jump start my car myself?
Yes. You need a second vehicle with a working battery and a set of jump leads, or a portable jump starter pack. Connect red (positive) to the dead battery's positive terminal, then to the running car's positive terminal. Connect black (negative) to the running car's negative terminal, then to an unpainted metal point on your car's engine block (not the dead battery's negative terminal). Start the running car, wait two minutes, then try starting your car. Once started, remove the leads in reverse order.
My car just clicked once and now nothing happens. What's wrong?
A single loud click followed by silence usually means the starter motor solenoid has engaged but the starter motor itself is not turning. Check that the battery terminals are tight and free of corrosion first. If the connections are fine, the starter motor or solenoid is likely faulty and needs replacement. This is different from a flat battery, which produces rapid clicking.
Can an immobiliser stop a car from starting?
Yes. All modern cars have an immobiliser that uses a transponder in the key to authenticate before allowing the engine to start. If the transponder battery in the key fob is dead, or the transponder chip is damaged, the immobiliser will prevent the car from starting even if the engine cranks over normally. Signs of an immobiliser fault include a security light flashing on the dashboard, or the engine briefly starting then immediately cutting out.
How do I know if my car battery needs replacing?
Signs of a failing battery include slow cranking speed (the engine turns over sluggishly), frequent need for a jump start, warning lights appearing, and age over five years. The definitive test is a load test, which applies a load to the battery and measures how much voltage it holds under that load. Many garages and motor factors will load-test your battery for free. A battery that fails a load test should be replaced.
How much does it cost to fix a car that won't start?
Cost depends entirely on the cause. A new battery (the most common fix) costs £80 to £180 including fitting. A starter motor replacement costs £150 to £350. A fuel pump replacement costs £250 to £600. Immobiliser reprogramming costs £80 to £200. Getting a diagnostic check first (typically £50 to £90) is the most cost-effective approach when the cause is not obvious from the symptoms.
What should I do if my car won't start and I'm stuck?
If you have breakdown cover, call your provider. If not, try a jump start first as a flat battery is the most common cause. If the car starts, drive to a garage promptly. If jump starting does not help, you will likely need a mechanic to diagnose and repair the fault where you are, or to have the car recovered to a garage. Post a job on AutoFixFair to get quotes from local mobile mechanics who can come to your location.