CraftsmanRepairService

Hello, I own a 1999 Jeep Cherokee 4L 6 Cylinder Sport. It threw 3 codes at me, PO135, PO138, and PO141 I believe it was. In result,I changed the o2 Sensors. Problem went away for about 30 miles of driving. Sure enogh, the codes came back, so I read up on the thread, and saw I have an o2 Sensor fuse. I checked it and sure enough, it was blown. I unplugged the - battery terminal, and changed the fuse. Drove it about 1 mile, and it's doing the same thing. Fuse is not blown either. Please help! Thanks in advance guys!

Turbo X_J

Electrical short? Is the wiring laying on the exhaust?

CraftsmanRepairService

Well from what I see, I'm not seeing any wires hitting the exhaust, but I'm kind of at a loss.

Turbo X_J

Something popped the fuse, they don't usually "wear out". Did you clear the codes after service?

tjwalker

Just to confirm, are you SURE that the fuse for the oxygen sensor heater circuit is not blown again? Maybe pop another one in there just for grins.

And are you seeing the exact same codes?

CCKen

To follow up on tjwalker's post, here's an image of the location of the O2S heater fuse in the PDC. This fuse, and the IOD fuse, are troublesome and worth installing the blow & glow type fuses in these locations so, if they are blown, they can be readily identified. These fuses can be purchased at O'reilly Auto Parts.



Here's an image of the location of the O2S heaters ground point.