Howdy! New member, first post. This forum has been a great help the past year but I really need some help! First about me - Not a mechanic, if you point, I can usually replace. When it comes to diagnosing, electrical, or carb or fuel forget it. I'm useless.
My issue - Bought the Jeep almost a year ago. It had a check engine light but ran fine so I assumed it was a down stream sensor. No biggie. Now I have to renew plates so I borrowed a friend's scanner. It came up with multiple codes. P0443 purge control, P0130 02 bank 1, sensor 1, P0136 02 bank 1 sensor 2 (p2270, p2271. Wasn't expecting all of that.
I decided first for grins to go to Napa and pick up a gas cap just in case it might eliminate a code. Swapped out the gas cap, ran the diagnostic and cleared the codes. I reset the trip to see how far I'd go before check engine came back on. Barely 1 mile. Pulled over, check the code. EVERYONE came back on. Couldn't believe it. Usually 5, 10, 20 miles. Not immediately!
I hate the idea of chasing parts 1 at a time, hard to come up with the possible $$$ outlay.
Any ideas would greatly appreciated. PLEASE

 

It could be a wiring issue. Sometimes critters chew wires. Could be a ground issue too. also could be an issue with the tubing causing a leak somewhere other than the gas cap. I don’t know my troubleshooting well enough to know if there is a single place that would cause all the faults to come up together but from my experience it seems like you get a line fault or a bunch together from a cascade of issues. To put it another way, lots of codes together might not be as bad as it seems.

 

Hey, thank you for the reply. It definitely makes sense. I'm assuming you're thinking about the tubing on the purge valve?
I'm not touching it today. No garage, near the Wis. border. Frickin' miserable out here - blowing snow wind. Miserable! I will definitely check it out the best I can tomorrow.

 

Actually, the downstream sensor(s) in 2000/2001 DO participate in fuel management.

You might try direct reading of the oxygen sensor signals with the OBD tester to confirm they need replacement.

 

Amazon $27.48.

But IIWM I'd check all the tubing and hoses from the gas tank forward (there's a metal tube that tends to rust out). Smoke tester can be helpful but the cheap ones work best if the distance between the tester and the leak is about 6 feet or less.

 

Thank You Dave51. More great insight along with Sworvoo's. Seems like both of you are somewhat going in the same direction on this. Much appreciation to both of you. Weather cleared so I'll be crawling around later today.
I'll let you guys know what i find.

 

Your OBDII tester should (might?) have the ability to look at real time data from the O2 sensors (you got 2 or 4?). This is from a $4.00 ELM327:

 

S1 should be like 0.6 volts S2 about 0.4 volts. If you see like a 1.0 or a 0.0 you know what to focus on.

 

I've been chasing strange issues with my XJ as well.

I replaced a EVAP purge valve due to code P0443 which returned shortly after. My next step is to test and or improve all my grounds.

 

I want to thank everyone for taking the time to try to help me. Only 1 problem. You were all wrong! You all assumed I had half a brain -wrong again!
As I stated, I had this issue when I bought it almost a year ago, but it ran fine, so I never bothered with it.
Found a fuse diagram on Utube for dummies. It showed a 15amp #10 slot fuse in passenger compartment. I went to check it to see if it was blown. It not only wasn't, but it wasn't even frickin' there!!! WTF
All the time I spent and the time ya'll wasted trying to help and I never checked the fuse.
Sincerely sorry.
Every day you learn something is a good day1
Thanks again. I'm sure you'll be hearing from me about something else soon.

 

Well technically it was a wiring issue 😝. And now you have a shiny new gas cap too.

 

IYAM, I'm thinking this story isn't over yet.

 

I wonder if I should return the gas cap? .....Naa. As far as being over yet - I just need another 13 miles before I bring it to emissions. Everyone keep their fingers crossed.

 

Passed emissions. Good for another year. MAYBE!