P0301: Cylinder 1 Misfire — Top Causes
Key Takeaway
P0301 points to cylinder 1. Here's what to check and fix.
What P0301 Means
P0301 = misfire detected in cylinder 1. The ECM counts misfires per cylinder using the crankshaft position sensor.
Top Causes for Single-Cylinder Misfire
| Cause | Likelihood | Fix Cost |
|---|---|---|
| Bad spark plug (cyl 1) | Very common | $20 – $40 |
| Failed ignition coil (cyl 1) | Common | $50 – $150 |
| Faulty fuel injector (cyl 1) | Moderate | $150 – $300 |
| Low compression (cyl 1) | Less common | $1,000+ |
| Wiring issue to coil/injector | Moderate | $50 – $200 |
Diagnosis Shortcut: The Swap Test
Swap the ignition coil from cylinder 1 with cylinder 2. Clear codes and drive. If the misfire moves to cylinder 2 (P0302), you've confirmed a bad coil. Same technique works with spark plugs.
ProHow Steer Helps
Steer pinpoints cylinder 1 and guides you through the swap test.
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