aqualordx93

hey all. Purchased a lovely XJ a few months back, now its starting to give me problems

I got codes:
P0135
PO141
P0155
P0165

It says all 4 of my O2 sensors heater circuits are bad, i checked my fuse, it was blown. replaced it and then that one blew. Getting TERRIBLE gas mileage and also idles very rough.

Any help or guidance would be greatly appreciated.

scottmphoto

Check the wiring going to the sensors. Sometimes the wires will get damaged and cause a short.

aqualordx93

Did.
No kinks or cracks or wires broken. Trying to figure out how ALL 4 sensors are like this though.

Stabsthedrama

I'd still be checking all of the wiring if I were you. I mean all the way to the fusebox. Not just the visible wire runs underneath the Jeep. Can't really think of a reason all 4 would be doing that except for an open or short in the wiring somewhere. The fuse is blowing because there's something wrong with wiring, I can pretty much garuntee that. Really get in there behind the fuse box, get some wiring diagrams maybe. Shoot down the wires with a DMM, etc. It's gotta be wiring (or the wrong fuse size, but I doubt you'd be making a silly mistake like that)

aqualordx93

Will do later today and ill let you know what i find.

CCKen

The one fuse (F17 20A) feeds all four O2S' through two relays (see PDC pic).

See if you can isolate which O2S or O2S' circuit(s) are blowing the fuse by removing the Upstream and Downstream relays one at a time, start the engine and see if the fuse blows. If it does, the circuit for the installed relay may be shorted to ground.

If the fuse blows with both relays removed. The short is between the fuse and relays. Power from the fuse goes to the Downstream relay then tees off at this relay and goes to the Upstream relay.

After leaving the relay(s), power goes through connector C107, which is located at the transmission oil dipstick tube (see pic). The wiring could be chafed at this connector or the connetor is contaminated in some way to short out the power wire(s). Both of the Downstream O2S' power wires from the relay are Violet/Orange tracer, and the wires for both of the Upstram O2S' are Dark Green.



C107 location:



Oxygen Sensors locations:



.

Stabsthedrama

See I can always rely on you to come and put my rudimentary troubleshooting advice to shame with technical expertise

DFlintstone

Yea, no -s-. "Don't stare directly at the welding". Ken should be on the payroll. My Renix don't need no stinkn welding.

CCKen

There's no shame in rudimentary troubleshooting. It would be nice if the peeps with issues would just use some common sense and do some looking, wiggling, etc., and searched their issue, before crying they have changed every sensor known to man on their Heeps and it hasn't fixed it and they can't figure out what's wrong.

And...buy a FSM. $7.95.

aqualordx93

AMAZING INFORMATION. Thank you, i really appreciate it. I just got my wisdom teeth out so im going to see how i feel tomorrow. I didnt know that the o2 sensors had relays, i did know that it had a fuse. Plan was to disconnect all the 02 sensors and put a fuse in and plug in sensors 1 by one, and once it blows hopefully that is a the problem. I traced all my wiring and found nothing damaged. Hoping its not a complicated fix.

Stabsthedrama

I learn through helping, so even if I'm not on the mark, with dudes like you around I put the pieces together. I've learned a lot about stuff I haven't even had to do yet cuz of this forum, and I find that extremely educational just in general, and not just as a Jeep hobby.

I feel your pain. Got mine taken out in the Air Force. Unfortunately a few weeks later I started having an agonizing shooting pain in my jaw. Turns out there was a huge bone fragment they had to scrape out of there again. Not. Fun.

aqualordx93

Damn, off topic but 1 of my bottoms they couldn't remove. The roots are around my nerve. If it was removed and they hit that nerve i would loose feeling in my lower lip for the rest of my life. I got 3 out today. Doing pretty well. How do you miss a bone fragment, sheesh. Glad you are good.

Stabsthedrama

Not only did they miss a bone fragment, no **** I went home, popped the vic's, fell asleep, woke up - went to the sink to clean out my mouth and found another bone fragment myself that just came right out and fell into the sink. Not even making this up. After that everything healed up just fine.

Feel better man let us know how everything goes.

aqualordx93

So good news i believe. I replaced the relays just because they are cheap and to know that they are good.
i unplugged both 02 upstream 02 sensors and replaced the fuse, started it up. Fuse didnt blow.
I plugged in bank 2 sensor 1 and started it back up, didnt blow.
I then plugged in the bank 1 sensor 1 and it poped right away. Thinking this is the fault.
Also i noticed that the plug wasnt "snug". I held it and my dad started the car and the fuse was ok, but then i just plugged it in normally and didnt put pressure on the plug and the fuse blew right away.
So im thinking i have a bad 02 sensor and connector on my Bank 1 sensor 1 02 sensor.