Hello all, I recently went about a mass maintenance extravaganza with my 99 4.0 automatic 4x4 XJ. Basically, I had put off a lot of maintenance and decided to go ahead and knock it all out in one go. Prior to everything, I had a check engine light for over a year for P0455 Large Evap Leak, and recently developed a P0204 injector circuit cyl #4 malfunction. The maintenance I did is as follows: New exhaust header (had an exhaust leak), new 12 hole injectors (so far solved the P0204 code, also haven't felt it misfire since), new track bar, new tie rod end, new motor mounts, new evap canister, new evap purge solenoid, and new leak detection pump. Now, I am confronted with a new issue; the jeep is running beautifully, however, I still have a check engine light. What makes it even more strange is that when I pull the codes, I get nothing, the code reader just displays 0 DTC. When I hit the link button, it checks for the I/M monitor statuses, and it appears the only I/M monitor not ready is the one for the evap system. Could the I/M monitor not being ready cause a check engine light with no codes? I've never seen anything like this before, so if anyone has some insight or advice it would be greatly appreciated.

 

Have you checked the codes with a different scan tool? Also check for blown fuses. Weird things can happen like that sometimes.

 

Just in case you havent already, disconnect the battery terminals and short them together for at least 30 secs to clear the PCM