General Information

Engine Control
P0304 Cylinder 4-Misfire detected - General Information

Component Location





General Description

Misfires can be caused by lack of combustion in a cylinder due to absence of spark, poor fuel metering, poor compression, or many other causes. Even a small number of misfires may result in excessive exhaust emissions due to the unburned mixture. Increased misfire rates cause damage to the catalytic converter. The ECM monitors the crankshaft speed variation to determine if any misfiring generated. The ECM identifies the specific cylinder in which the misfire has occurred and counts individual misfire events by monitoring changes in the crankshaft rotation for each cylinder. A random misfire indicates one or more cylinders are misfiring.

DTC Description

If there happen misfires over the threshold value at #4 cylinder, ECM sets DTC P0304.

DTC Detecting Condition





Diagnostic Circuit Diagram