Symptom guide
On this page
- Step 1: Turn the key and listen (30 seconds)
- No-crank: silence
- Check 1: interior lights and dashboard
- Check 2: battery terminals
- Check 3: try jumping it
- Check 4: gear selector
- No-crank: single click
- Check 1: voltage drop during click
- Check 2: voltage at the starter
- Check 3: the "tap test"
- No-crank: rapid clicking
- Slow crank
- Cranks but won't start
- Check 1: fuel pump prime
- Check 2: fuel pressure
- Check 3: spark test
- Check 4: scan for codes
- Check 5: try starting fluid (gas engines)
- Common causes ranked
- What it costs
- When to tow versus jump it
- Related guides
Car Won't Start: A 5-Minute Triage
Step 1: Turn the key and listen (30 seconds)
This is the single most important question in the whole diagnostic. What do you hear when you turn the key?
- Silence. Nothing happens. Suspect a dead battery, broken neutral safety switch, ignition switch, or wiring. Jump to No-crank: silence.
- One loud click, then silence. The starter solenoid pulled in but the motor didn't turn, usually a battery or starter problem. Jump to No-crank: single click.
- Rapid clicking (clack-clack-clack). The battery is too weak to spin the starter. Jump to No-crank: rapid clicking.
- Slow, lazy crank, no fire. Suspect a weak battery, bad ground, or worn starter. Jump to Slow crank.
- Normal cranking but won't fire. Look at fuel, spark, or a sensor. Jump to Cranks but won't start.
No-crank: silence
The starter isn't even trying. Either the solenoid never got the "start" signal, or there's no battery voltage to deliver.
Check 1: interior lights and dashboard
Turn the key to ON without trying to start. Do the dashboard lights illuminate? Does the radio power up?
- Lights normal, radio works: the battery is at least partly alive. Suspect the ignition switch, neutral safety switch (auto), clutch switch (manual), or starter relay.
- Lights very dim or off: the battery is dead or a terminal is loose. Move to the battery test.
Check 2: battery terminals
Wiggle each terminal. A terminal that moves under hand pressure can cause a no-crank all by itself. Tighten it with the appropriate wrench, then retest.
Check 3: try jumping it
Run jumper cables from a known-good vehicle, give it 2–3 minutes to transfer charge, then try to start. If it cranks normally now, the battery was the issue. Drive for 30 minutes to recharge.
Check 4: gear selector
On an automatic, try starting in N instead of P. If it works in N, the neutral safety switch (range sensor) needs adjustment or replacement.
On a manual, hold the clutch fully to the floor. Some manuals require a clutch pedal switch to close before the starter can engage.
No-crank: single click
The solenoid heard the start signal but the motor didn't spin. The two likeliest causes are these:
- A battery too weak to spin the starter under load. Crank-amp delivery falls below spec even if the resting voltage looks fine.
- A failed starter motor (worn brushes or a shorted armature).
Check 1: voltage drop during click
Connect a voltmeter to the battery terminals while a helper tries to start. If voltage collapses from 12.6 V to below 9 V at the moment of the click, the battery is the issue. Replace it.
Check 2: voltage at the starter
If battery voltage holds during the click, probe the starter B+ terminal directly with a voltmeter and repeat the start attempt. Full battery voltage at the post with no spin means the starter is dead.
Check 3: the "tap test"
Have a helper hold the key in START. Tap the round motor section of the starter with a hammer, not the solenoid. If the starter spins up after a tap, the brushes are worn and stuck. Replace the starter; you've just bought yourself one more start.
No-crank: rapid clicking
This is the classic dead-battery sound. The solenoid contacts close, the starter draws current, voltage collapses, the solenoid drops out, voltage recovers, and the solenoid pulls in again, over and over: clack-clack-clack.
Diagnosis: load test the battery. A healthy 12 V battery holds 9.6 V or higher under a 50% load test for 15 seconds. Anything lower needs replacement.
If the battery passes the load test, the trouble is high resistance somewhere in the starter circuit, such as corroded cable ends, a bad ground strap from engine to chassis, or an internal cable break.
Slow crank
The engine spins, but lazily, as if one cylinder fired before stopping.
- Weak battery. Load test it.
- Bad ground strap from engine to chassis. Inspect it visually, then clean the bolts and contact points.
- Worn starter motor. Less common than the battery and ground cases.
- Engine seizure or hydrolock. Rare, and usually obvious from the sound, which is a hard thunk rather than a slow grind.
Cranks but won't start
The starter is doing its job, but the engine isn't catching. The trouble falls into a few broad categories.
- No fuel: an empty tank, a dead fuel pump, a plugged filter, or no pump prime.
- No spark: a dead crankshaft position sensor (
P0335), a failed coil, or a bad ignition switch. - No ignition trigger: the sensors that fire the system are unresponsive.
Check 1: fuel pump prime
Turn the key to ON without cranking. Listen at the gas filler cap, or under the rear seat on most cars, for a faint 2-second buzz as the fuel pump primes. A pump prime means the fuel system has voltage. No prime points to the fuel pump or its relay or fuse.
Check 2: fuel pressure
If you have a fuel pressure gauge, check at the rail's Schrader port. The spec varies, typically 40–60 psi for port injection and much higher for GDI. Zero or low pressure points to the pump, regulator, or filter.
Check 3: spark test
Pull one ignition coil and a spark plug, ground the plug to the engine, and crank. A visible blue spark at the plug means the ignition is working. No spark points to the coil, the CKP sensor, or related electrical.
Check 4: scan for codes
Connect an OBD-II scanner with the key on and the engine off. Codes
already stored will tell you which subsystem the PCM has flagged. A
P0335 (CKP sensor) is a common no-start cause that
sets even before the engine catches.
Check 5: try starting fluid (gas engines)
A small spray of starting fluid into the intake while cranking will make a gas engine fire briefly if the ignition system is working. If the engine catches on starting fluid, you have a fuel delivery problem. If it still won't catch, the trouble is ignition or compression.
Common causes ranked
| Cause | Approx. % of no-start calls | Fix cost (USD) |
|---|---|---|
| Dead battery | 35% | $120–$280 (battery) |
| Worn or failed starter | 15% | $180–$450 (starter + labor) |
| Corroded battery terminals | 10% | $0–$15 (clean) |
| Fuel pump failure | 10% | $400–$900 (pump + labor) |
| Crankshaft position sensor | 8% | $80–$250 (sensor + labor) |
| Empty fuel tank | 5% | $30–$80 (fuel) |
| Failed ignition coil(s) | 5% | $60–$300 (coil + labor) |
| Neutral safety switch | 3% | $80–$250 |
| Wiring or fuse | 3% | $5–$200 |
| Ignition switch | 2% | $120–$300 |
| Other (timing belt, fuel filter, etc.) | 4% | varies |
What it costs
| Diagnosis path | DIY | Shop |
|---|---|---|
| Battery replacement | $120–$220 (battery only) | $180–$320 |
| Starter replacement | $180–$350 | $300–$650 |
| Fuel pump replacement | $250–$600 | $500–$1,200 |
| CKP sensor | $30–$100 | $150–$400 |
A shop tow plus diagnostic on a no-start typically runs $150–$300 on top of the fix itself. If you're a member of an auto club (AAA or similar), the tow may be free.
When to tow versus jump it
- Battery is dead and you have cables: jump it, drive for 30 minutes to recharge, then replace the battery at your convenience.
- Engine cranks but won't start: tow it. You can crank for hours without solving the problem and only flatten the battery in the process.
- Starter clicks once and refuses to spin: tow it. A failing starter that works after a few taps will leave you stranded somewhere worse.
- No-crank with no power to anything: check the battery cables; if a terminal is just loose, tighten it and try again. Otherwise tow it.