P0301: Cylinder 1 Misfire Detected
Cylinder 1 is misfiring - the combustion event in that cylinder is failing or incomplete. This is like one of your engine's pistons not doing its job, causing rough running and potential catalytic converter damage.
Symptoms
- Rough idle (feel vibration)
- Check engine light (may flash)
- Loss of power
- Poor fuel economy
- Possible raw fuel smell
Causes (Ranked by Likelihood)
50 Most Common OBD2 Codes - Free Printable
Plain-English explanations for the codes mechanics charge $100+ to diagnose.
No spam. Unsubscribe anytime.
DIY Fix Steps
⚠ Safety first: work on a cold engine, chock wheels, use jack stands - never rely on a floor jack alone.
Move the coil from cylinder 1 to another cylinder (e.g. cylinder 3). Clear codes. If misfire moves to cylinder 3, the coil is bad. Cost: $20-80.
Even if coil swap confirms bad coil, replace the spark plug too. Misfires damage plugs. Use OEM or NGK/Denso equivalent. Gap to spec.
If coil and plug are fine, listen to injector with a mechanics stethoscope (or screwdriver to your ear). No clicking = dead injector. Use injector cleaner first ($10).
Remove spark plug from cylinder 1. Thread in compression tester. Crank 5 seconds. Should read 130-180 PSI. Less than 100 PSI = internal engine issue.