ok, i have a G4 that i have been working on off and on for a year. Got it all sorted and let me father in law drive it. No codes nothing. He gives it back with the starter acting up and O2 sensor codes. Nothing else.

I replaced the starter and all 4 o2 sensors. Started up and drove it for 200 miles and ran GREAT, As im pulling in my driveway from driving back and refilling the tank. It started running rough and check engine light comes on. I cleared it and drove again and same codes. P0134, P1000, P0300, P0301, P0302, P0305, P0307. WTH. All new plug wires and plugs before I gave it to my father and law. Has new battery. Have never had this many codes on this rig. its always been 02 related. Any help is appreciated. i am tired of having to revisit this Disco about this.

THanks Everyone

 

My guess is you still have the coils in the factory location, because troubleshooting a misfire after you move them is cake. No idea what 134 and 1000 are, I don't memorize them, but I kind of doubt they are serious. You might want to post the reason codes.

 

I’m gonna go zero to apocalypse: did he let it get hot? How are your temps? Might want to do an exhaust gas test, and hopefully I’m very wrong.

 

Four cylinders are misfiring. Could be coil problem. Could also be related to re-filling the tank just prior to the problem? Start with fixing the misfires, like Extinct mentions often, misfires are usually ignition related.