Which Cylinder Is Misfiring? P0301-P0312 Code Helper

Cylinder 1: Usually closest to the front of the engine (belt side).
Bank 1: The side of the engine that contains cylinder 1.
Verify numbering: Always confirm with a service manual or under-hood label.

Decode Your Misfire Code

Use short and long term fuel trim readings to spot lean or rich faults.

Interpret vacuum readings and needle behavior during engine diagnosis.

Compare cylinder compression readings and flag weak cylinders.

Check charging voltage, ripple, and cable voltage drop readings.

Estimate how long a key-off current draw can drain the battery.