My Car Won't Start and Just Clicks — What Now?

One click or many? Start here

Turn the key or press the button, listen carefully, and put what you hear into one of three groups.

The reasoning behind the split is worth understanding, because it makes the rest obvious.

The starter solenoid does two jobs at once: it throws a gear into the flywheel, and it closes a very heavy electrical contact to feed the starter motor. Both need current.

Rapid clicking happens when there is just enough power to pull the solenoid in but not enough to keep it there once the motor starts drawing. It pulls in, voltage collapses, it drops out, voltage recovers, it pulls in again — several times a second. That is the sound of insufficient current, and insufficient current means the battery or the path to it.

A single heavy clunk means the solenoid pulled in and stayed in, so the current was adequate for that, but the motor did not turn. That points at the motor itself — or at a battery that is strong enough for the solenoid and not for the motor, which is why a weak battery can also produce this.

The headlight test, which costs nothing

This is the single most useful thing you can do, and it takes twenty seconds.

Turn the headlights on, leave them on, and try to start the engine while watching them.

• The lights go out completely or dim to almost nothing when you turn the key → the battery cannot supply the current, or the connections cannot carry it. Charge, jump or clean before replacing anything.
• The lights stay bright and steady, and you get one click → the battery is delivering plenty. That points at the starter motor or its heavy cable, not the battery.
• The lights dim slightly and you hear the engine turn over slowly → a weak but not dead battery, or a very cold morning. Different problem, but the same solution to start with.
• The lights were already dim or orange before you touched the key → the battery is flat. This is where most of these end.

People often say "the dashboard lights up, so the battery is fine". That does not follow. Dashboard lights draw a fraction of an amp; a starter motor draws several hundred. A battery can light every warning lamp on the dash brightly and still be incapable of turning the engine. The headlight test is meaningful precisely because it puts a real load on.

Terminals and the earth strap

This is the cause people skip, and it produces exactly the same symptoms as a dead battery on a battery that is perfectly healthy.

Open the bonnet and look at the battery posts. What you are looking for:

• White, blue or green crusty powder around either terminal. That is corrosion, it is an insulator, and even a thin film of it chokes the several hundred amps a starter needs.
• A terminal you can rotate by hand. A clamp should be immovable. If it twists at all, it is not making proper contact — and this alone causes a large share of clicking no-starts.
• The earth strap, the heavy cable from the negative terminal to the body and the engine block. It corrodes at its ends and behind its bolt where you cannot see it. A poor earth is one of the most common and most misdiagnosed causes there is, and it produces the full flat-battery symptom set on a fully charged battery.
• The heavy positive cable to the starter, which can corrode inside its insulation, particularly on older or salt-exposed cars.

If a terminal moves, tightening it may start the car immediately. If there is corrosion, disconnecting (negative first), cleaning both posts and clamps back to bright metal, refitting tightly and reconnecting (negative last) is a genuine repair, not a bodge.

A telling clue: if the car started fine yesterday and clicks today with no gradual decline, a connection is a more likely culprit than a battery, because batteries usually fade over days or weeks rather than overnight. The exception is a sudden cold snap, which can push an already-weak battery over the edge in a single night.

When it is simply the battery

Most of the time it is. What supports it:

• The battery is more than about four or five years old. That is the point where failures become common, and they tend to be abrupt.
• It has been getting slower to start for a while, especially on cold mornings.
• Something was left on — headlights, an interior light, a door not shut properly, a boot lid ajar.
• The car does very short journeys and rarely gets a long run. Starting takes a large slug of charge, and a fifteen-minute trip does not fully replace it. Over a winter, that arithmetic runs the battery down permanently.
• It has been standing for weeks. Modern cars draw a small constant current for alarms, keyless entry and modules, which flattens a battery over a few weeks of inactivity.
• The first cold night of the season. Cold reduces the current a battery can deliver while simultaneously making the engine harder to turn, which is why so many batteries "fail" on the same morning across a whole city.

If a jump start works and the car then runs fine, the battery was the problem — but ask why. A battery that goes flat repeatedly is either at the end of its life, not being charged properly by the alternator, or being drained by something. If your battery warning light stays on while driving after a successful jump, the alternator is not charging and the car will stop again once the battery is exhausted.

When it really is the starter

Starters do fail, generally after a long life and usually with warning. What points at it:

• Bright, steady headlights during the attempt, plus a single solid clunk. Power is clearly available and the motor is not using it.
• A jump start makes no difference at all. Adding a good battery to a working circuit should overcome a weak one; if nothing changes, the fault is downstream.
• Intermittent behaviour over weeks — sometimes it starts, sometimes one click, and it seems random. That is classic worn brushes or a dead spot on the armature.
• A grinding or whirring noise during the attempt rather than a click, which indicates the gear is not engaging with the flywheel properly.
• It starts after the car has been left for a few hours but not when hot. Heat soak from the exhaust affects a tired starter.

You may have heard the trick of tapping the starter with a mallet while somebody turns the key. It does sometimes work, by jarring worn brushes back into contact — and if it works, that is a diagnosis rather than a repair: the starter is on its way out and will strand you again. It also involves reaching into a running-capable engine bay, so it is not something to attempt casually.

What a jump start proves

A jump start is a diagnostic tool as much as a way of getting home, provided you pay attention to the result.

• It starts immediately and runs normally → the battery, its charge, or its connections. Drive for a decent run, then have the battery and charging system tested.
• It still clicks with the leads on → not the battery. Either the leads are not making good contact, or the fault is in the connections or the starter. Wiggle and reposition the clamps and try once more before concluding.
• It starts, then dies as soon as the leads come off → the alternator is not charging, and the car has been running on borrowed power.
• Nothing at all, not even a click, with the leads on → look further upstream: the immobiliser, the ignition switch, a starter relay, a fuse, or the safety switch below.

Connect the leads in the standard order — positive to the flat battery, positive to the good battery, negative to the good battery, and the final negative clamp to a solid unpainted metal point on the flat car's engine or chassis, away from the battery. Leave the donor running for a few minutes before attempting to start. Modern cars have sensitive electronics, so it is worth checking your handbook, and some manufacturers specify particular jump points rather than the battery itself.

Clicks that aren't the starter at all

Worth ruling out before anyone charges you for a starter motor.

• The safety switch. An automatic will not crank unless it is properly in Park or Neutral; a manual often will not crank unless the clutch is pressed fully. Try Neutral instead of Park, press the clutch to the floor, and rock the gear selector. A worn switch or a slightly misplaced selector produces a car that seems dead and is fine.
• The immobiliser. A key fob with a flat coin cell, or a transponder that is not being read, can stop the car cranking. Many cars have a marked spot on the steering column or the start button where you hold the fob to read it directly — check your handbook, because it takes seconds.
• A blown fuse or a failed starter relay. Relays are inexpensive and often identical to another relay in the same box, so swapping two is a quick free test on many cars.
• A seized engine or a seized accessory. Rare, and serious. If the starter clunks and the engine will not turn even with a good battery, that is a reason to stop rather than to keep trying.
• A flooded engine or a fuelling problem — but note that these produce an engine that turns over and does not fire, which is a completely different sound from clicking. If it cranks, this page is not your problem.

What to check, in order

1. Listen. Rapid clicking, one heavy clunk, or a faint tick from the dash — decide which before touching anything.
2. Headlight test. Lights on, turn the key, watch them. Big dim means power; steady bright means the starter side.
3. Automatic: try Neutral. Manual: press the clutch fully. Free, and a genuine fix surprisingly often.
4. Check nothing was left on overnight, and that no door or boot is ajar.
5. Try to twist each battery terminal by hand. Any movement at all means it is not making contact — tighten it.
6. Look for crusty corrosion on the posts, and follow the earth strap to where it bolts to the body and the engine.
7. Try the spare key, or hold the fob at the marked reading point, to rule out the immobiliser.
8. Jump start it, and note carefully what happens — that result is your diagnosis.
9. Swap the starter relay with an identical one in the fuse box, if your car has one.
10. Still one clunk with bright lights and a good jump → the starter. That is a workshop job.
11. Once it is running, have the battery and the charging system tested rather than assuming it is fixed.

Stopping it happening again

• Have the battery tested once a year before winter. Most parts shops and garages do it free in a couple of minutes, and it turns a roadside failure into a planned purchase.
• Clean and grease the terminals when you replace a battery, and check them at every service.
• Give the car a proper run at least every week or two if you mostly do short journeys. Half an hour of steady driving does far more for the battery than several short trips.
• Use a trickle charger or maintainer if the car stands for long periods. Far cheaper than the batteries it saves.
• Replace the battery on age, not on failure, once it is past about five years — particularly if you rely on the car.
• Check the earth strap if you ever have unexplained electrical oddities. A poor earth causes strange, intermittent faults all over a car, not just at the starter.
• Change the key fob battery when the range starts dropping, rather than waiting for it to strand you.
• Keep jump leads or a lithium jump pack in the boot. A jump pack starts the car without a second vehicle, and it is one of the few genuinely useful things to carry.