The car cranks forever but never starts — what's the first thing to check?

Get a free OBD2 scan at AutoZone or O'Reilly before spending any money. A P0335/P0336 points to the crankshaft sensor; P0230/P0231 or no fuel pressure points to the pump. If no codes, listen for the fuel pump prime sound (a 2-second buzz when you turn the key to 'On') and confirm there's actually gas in the tank.

My car cranked and started fine this morning but now won't start. What happened?

Intermittent no-starts that worsen when the engine is warm often point to a crankshaft position sensor that is failing under heat, or a fuel pump that can't maintain pressure when it gets hot. A free scan is still the first step — heat-related failures sometimes set codes even between incidents.

Can a car crank but not start because of a bad ignition coil?

Yes, especially on a 4-cylinder engine. If all coils fail simultaneously (rare but happens on some coil-pack designs) the engine gets no spark and cranks endlessly. Check for codes P0300–P0312 (misfires) or P0350–P0362 (coil faults). A single bad coil causes a rough misfire, not usually a no-start.

How do I check for spark without special tools?

Remove one spark plug wire (older cars) or a coil-on-plug connector, insert a spare spark plug, and rest the plug's base against the engine block. Have a helper crank the engine while you watch — you should see a bright blue spark. An orange or yellow spark is weak. No spark at all confirms an ignition problem.

Car Cranks But Won't Start: What the Sound Tells You

Plain-English explanation

When the engine cranks — that rr-rr-rr-rr sound — it means the battery and starter motor are doing their job: they are spinning the engine. But the engine is refusing to actually fire up and run on its own. Think of it like a campfire that has a working lighter but the wood is wet (no fuel), or the kindling is missing (no spark), or the wind is blowing wrong (a sensor is lying to the computer). The starter is innocent. The problem is fuel, spark, or information.

Most likely causes — ranked

Failed fuel pump

🔴 most likely

Driveway Pinpoint Test

Turn the key to the 'On' position (engine off, don't crank yet) and listen near the fuel tank — you should hear a brief 2-second whirring or buzzing sound as the pump primes. No sound at all strongly points to a dead pump. Also check the fuel gauge; an inaccurate gauge can trick you into thinking the tank is full.

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DIY Cost

~$200

parts only

Shop Cost

~$550

parts + labor

If you skip it

A dead fuel pump means the car will not start at all. There is no workaround. You will need a tow. Delaying diagnosis while cranking repeatedly can also drain the battery and damage the starter.

Bad crankshaft position sensor

🟠 likely

Driveway Pinpoint Test

Plug in a free OBD2 scanner (AutoZone and O'Reilly do this for free). A code P0335 or P0336 confirms the crankshaft sensor is not sending a signal. Without this signal the ECU can't time the fuel injectors or spark — so the engine cranks but never fires. The car may also have worked fine, then suddenly refused to start after sitting in the heat.

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DIY Cost

~$35

parts only

Shop Cost

~$220

parts + labor

If you skip it

A dying crankshaft sensor often fails intermittently first — the car won't start, then mysteriously starts later after it cools down. Ignoring it means you'll eventually be stranded with no restart possible.

Fouled or worn spark plugs

🟡 possible

Driveway Pinpoint Test

Pull one spark plug and inspect the tip. A healthy plug is light tan or gray. A fouled plug is black and sooty (too rich) or oil-coated (oil burning). A worn plug gap is easy to check with a gap tool. Misfires may also show as P0300–P0312 codes on a free OBD2 scan.

Fix-vs-Skip Money Panel

DIY Cost

~$30

parts only

Shop Cost

~$160

parts + labor

If you skip it

Severely fouled plugs can prevent a cold-start entirely. Continued cranking with fouled plugs pushes raw fuel into the catalytic converter, which can destroy it — a $1,500+ repair.

Get a FREE OBD2 scan first — no purchase required

AutoZone, O'Reilly Auto Parts, and Advance Auto Parts all scan your car's computer for free. Walk in, they plug in a scanner, you get a code in under 2 minutes. Then come back here and look up that code at eli5cars.com/obd2 for the plain-English explanation.

Pro tip: Take a photo of the code before they clear it.

Watch the repair

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Car Cranks But Won't Start: What the Sound Tells You

Most likely causes — ranked

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Get a FREE OBD2 scan first — no purchase required

Watch the repair

Frequently asked questions