# 4 cylinder misfiring on 1998 gmc safari code PO304

Explanation and repair suggestions at the link below...

https://www.obd-codes.com/p0304

P0300 random misfire, p0302 cylinder 2 misfire, p0304 cylinder 4 misfire, p0411 secondary air injection system incorrect flow detected, p1296 cooling system malfunction

Code PO304 means that Cylinder number 4 is misfiring.

PO300 and P1399 are random cylinder misfire detected.
PO301 cylinder 1 misfire
PO302 cylinder 2 misfire
PO304 cylinder 4 misfire
PO306 cylinder 6 misfire
I would say that you have damage to the ignition wiring harness or you ECM is failing.

The code PO304 means that cylinder 4 is misfiring and it could be that the sparkplug is bad and needs to be replaced or sometimes it could be the sparkplug wire

PO304 --is a misfire on cylinder # 4
The 171 is an O2 code from the misfire

Care to say what vehicle you have!

P0304 indicates misfire in the cylinders..
A misfire can be triggered by several situations. inadequate fuel, ignition misfire, insufficient air flow, too much fuel, incomplete compression... If you look at freeze frame data with a scanner you can see what the conditions were when the code was set, this will really help to pinpoint the problem.

might be the coil pack is bad, wires, plugs, o2 sensors, dirty injectors, catalic converter ( only if you smell rotten eggs ) . cylinders are misfireing.

complete tune up plugs wires distributoe cap and rotor

Disconnect battery for 30 seconds then reconnect that will reset code or it takes about 35 start cycles