When a car will not start, the first question is what it does when you turn the key or press the start button. If nothing happens or you hear clicking, the problem is usually the battery, the connections or the starter. If the engine cranks normally but will not fire, it is missing fuel, spark or a crankshaft signal. If it starts and immediately dies, suspect the anti-theft system, fuel pressure or idle control.
1. No crank, or clicking
- Weak or dead battery: the most common cause. A healthy, fully charged battery reads about 12.6 volts with the engine off; around 12.2 volts or less means it is weak. Rapid clicking and dim dash lights point here.
- Corroded or loose battery cables: clean and tighten both terminals and check the engine ground strap.
- Failed starter or starter solenoid: a single loud click with bright dash lights is a classic starter symptom.
- Shifter not reading park or neutral: a faulty transmission range sensor can stop the starter; try starting in neutral.
- Seized engine: if the starter strains but the engine will not turn, see spun rod bearings and seized engines.
Bad battery vs bad starter vs bad alternator
| Symptom | Most likely |
|---|---|
| Rapid clicking, dim lights | Weak battery or poor connection |
| One click, lights stay bright | Starter or starter solenoid |
| Starts with a jump, dies again later | Charging system; see bad alternator symptoms |
| Grinding when cranking | Starter drive or damaged flywheel teeth |
2. Cranks but will not start
- No fuel: listen for the fuel pump humming for a couple of seconds when the key turns on; see fuel pump symptoms and P0087 on diesels and direct-injection engines.
- No crank signal: a failed crankshaft position sensor stops both spark and fuel; if the tachometer does not move while cranking, see P0335.
- No spark: a failed ignition module, fuse or relay.
- Broken or jumped timing belt or chain: the engine cranks faster or sounds uneven; see timing chain symptoms and do not keep cranking.
- Flooded engine after short cold starts, or a security light flashing on the dash (key not recognized).
3. Starts, then dies
Immediate stalling after a start often means the anti-theft system does not recognize the key. Stalling a few seconds later points to low fuel pressure, a dirty throttle body or idle control (see P0505), or a large vacuum leak.
What to check first
- Battery voltage and clean, tight terminals
- Dash warning lights, including the security light
- Fuel level and the fuel pump prime sound
- Stored codes with a scan tool; see our OBD2 codes list
If the engine turns but has no compression, or has seized, a replacement may make more sense than a repair; see how to tell if an engine is blown and our engines.
More guides: car battery voltage chart · transmission range sensor · fuel filter · how to jump start a car · car won’t start, just clicks · bad starter symptoms · car battery dies overnight.
Trouble codes: P0230 Fuel Pump Primary Circuit · P0685 ECM Power Relay Circuit · U0167 Lost Communication With Immobilizer · P0231 Fuel Pump Secondary Circuit Low · P0688 ECM Power Relay Sense Circuit · P0850 Park/Neutral Switch Input · P0322 Engine Speed Input No Signal · all OBD2 codes.
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