Intermittent random misfire (P0300) - any ideas? -
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back > Models > Jeep Liberty Forums > KJ Liberty Forum > Intermittent random misfire (P0300) - any ideas?

FS: Jeep Fog Light LED Bulbs! Several Brightness Options! SPARTAN LOCKERS are on sale BIG TIME at ROCKRIDGE 4WD!Yukon Ultimate 35 axle kit for c/clip axles with Yukon Zip

Unread 06-14-2013, 12:34 PM   #1
Web Wheeler
1993 ZJ 
Join Date: Apr 2007
Location: UK
Posts: 2,264
Intermittent random misfire (P0300) - any ideas?

My 2005 KJ has new plugs and coils and a new battery. Once every couple of weeks I'll get a CEL for the P0300 random misfire code. I'll reset it, and everything will be fine for another couple of weeks, and then it'll be back again. I'm not actually aware of the engine misfiring, and since the P0300 refers to multiple cylinders, I figured I *would* notice.

Any suggestions for things to check *other than* plugs, coils and battery? Could it possibly be the camshaft sensor (or similar) going bad? All the engine sensors are the 2005 factory originals, bar the O2 sensors, which have been changed once.

AVR2 is online now   Reply With Quote
Unread 06-14-2013, 08:01 PM   #2
Registered User
2004 TJ Wrangler 
Join Date: May 2013
Location: Cape Cod, MA
Posts: 23
Misfires can ALSO be caused by faulty wiring to the coil, clogged/faulty fuel injectors, coolant leaks into the cylinder, bad fuel, low fuel pressure, carbon buildup and a faulty ECM. Based on my understanding, the P0300 is a generic fault that does NOT identify the exact cylinder or cylinders that are the problem. It does not necessarily mean more than 1 cylinder is misfiring. You will need to get a hold of a scan tool that can provide you the specific cylinder misfire otherwise youll be throwing parts at all the cylinders. There are a boat load of diagnostics that can be performed to identify the source or at least eliminate some of the causes.
ppap is offline   Reply With Quote

Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. is not in any way associated with Jeep or the Chrysler Corp.