P0301: Cylinder 1 Misfire Detected

Cylinder number 1 is misfiring.

High Severity

$50 – $500

Typical repair cost range

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Can I Keep Driving with Code P0301?

Avoid driving long distances. A flashing CEL means stop driving.

What P0301 Means

Cylinder 1 is not firing consistently. Causes range from a worn plug or weak coil on that cylinder, to a clogged injector, low compression, or a vacuum leak affecting that cylinder.

Common Causes

Bad spark plug in cylinder 1 — see repair cost
Failed ignition coil on cylinder 1
Clogged fuel injector — see repair cost
Low cylinder compression (worst case)

Diagnostic Tips

Swap the coil and plug from cylinder 1 with cylinder 2. If the misfire follows, you know which part is bad.
If swapping does not help, do a compression test before deeper diagnosis.

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Frequently Asked Questions

Where is cylinder 1?

Depends on your engine, look up the firing order for your make and model. Usually it is the cylinder closest to the front of the block on one side.