Decemberist

I really try not to ask too many questions about my Jeep here on the forum but this one I’m going to need some help on. My 2000 xj has been idling a bit rough in the colder mornings for a couple of weeks now it gets better once it’s warmed up. Yesterday it was idling and grew the code p0175 rich fuel mixture bank 2. It also had a number 4 cylinder misfire. I have looked this up online but there is not too much info on this. Any help would be appreciated my jeep is in excellent condition for being in NY for its entire life and hope to keep it that way.

EZEARL

https://www.engine-codes.com/p0175_jeep.html

VTJeep

Hmm.. The misfire could be due to fuel mixture issue. o2 sensors determine the A/F ratio so maybe a bad o2 sensor is to blame. I had long standing issues with upstream sensor that turned out to actually be a problem with the ignition coil but I’m pretty sure you’re distibutorless?

extrashaky

I would suspect one or more oxygen sensors feeding the computer bad data. The misfire could be caused by the engine computer attempting to correct for the bad info. When was the last time the O2 sensors were replaced?

Tbone289

Is this a CA emissions vehicle, or Federal emissions?

Decemberist

it’s CA emissions which means I had to replace both upstream NTK O2 sensors which seemed to have solved my problem, (not going to worry about the down streams). I guess I’ll know for sure when I start it up tomorrow morning in Upstate NY freezing 27 weather. I should have known because it has 140k and I doubt the PO ever changed them.

Tbone289