P0301
HighP0301 — Cylinder 1 Misfire Detected
Description
What This Code Means
The DME logs misfires in cylinder 1. P0301 points to that specific cylinder, not random misfires across all of them.
On N55 engines, nine times out of ten it's the coil or the plug. But a bad injector — or low compression — will throw P0301 too.
Symptoms
Symptoms
- Check Engine light on the dash
- Rough idle, vibration
- Loss of power
- Possible drop into limp mode
Causes and fixes
Diagnosis and Repair
- Swap the ignition coil from cylinder 1 to another cylinder. If the misfire follows the coil, the coil is bad. Replace it (OEM
12138616153). - Inspect the cylinder 1 spark plug (OEM
12120037563). - Check the cylinder's injector for leaks and failure.
- If the steps above don't turn up the cause, run a compression test.
Possible secondary damage
Indirect Problems
- Continuing to drive with misfires damages the catalytic converter and oxygen sensors.
- Unburned fuel washes the oil film off the cylinder walls, which speeds up wear.