My WJ is displaying the check engine light and throwing error code P0601. Reasearch has led me to believe the only way this can be fixed is by replacing the PCM. I would rather not do this as it is a $200 fix.
My MPGs have not decreased. My engine seems to be running just as well as before the error code.
Is there any benefit to replacing the PCM besides losing the check engine light?
Can I just pick up a junkyard PCM, or does it need to be professionally reprogrammed with my VIN (or some other crazy stuff)?
I did a little research and found many people cure the code by replacing the PCM. I can't really answer your other questions but thought I'd verify what you've found. Being that you have no driveability issues, have you tried disconnecting the battery for a half hour to see if it clears the code? If it comes back, you'll know it's probably there to stay.
If the car runs fine and you do not have emission inspections in your area than I say it's up to you to decide if it's worth it to replace it. Personnaly, I would drive it, but I don't like working on my own cars unless I have to.
ASE Certified Master Automobile Technician and Master Truck Technician
I'm wondering the same thing. (Needing a PCM). I have this incessant erratic idle problem. I have had all the sensors which could possibly effect the idle changed, and it still happens. My go-to mechanic is at a loss (and he's a LONG TIME Jeep only guy), says there are gremlins in the electrical system that he simply can not locate/eradicate. As an aside, I changed the oil sending unit as I would ocassionally get a "0 pressure" reading. Bad unit, broke apart when removed. NOW...I get a "P0523" code (sending unit problem)! AND I STILL have this awful idle problem with no codes at all related to any other sensors or idle issues!
OK, I guess I'm just venting, but this is driving me crazy. Anyone interested in a '99 loaded, gorgeous GC Limited with 67K?