O2 sensor connector wiring fried

[Bozz80]

1998 323 throwing P0130 and P0135 codes. O2 sensor in bank 1 sensor 1 looks new but the wiring from the connector to the wiring harness looks like the power line (red) fried the insulation, melted the other wires and loom and completely burnt itself out in parts. Now I am having trouble tracing the wire back.

In most videos (and in my other BMW), there are 02 sensor connectors near the fuel rail but in this car it seems like the connector goes right to the wiring harness from behind the engine.

Is there another way to pull this wire without taking off the intake manifold?

If I can fix this, will it burn out again?

[Eric93se]

So, this isn't going to be easy but your going to have to examine ALL the wires to find all short or burnt wires. If you know basic wiring/electronics and know how to use a soldering iron and shrink tubing its really not that hard, just don't be one of those people that twist wires together, I had that shit on some of the wiring on my car and its F'ing BS.

I would start by disconnecting the Neg on the battery. You have to follow all the wires, definitely go into the long black box that is attached to the top of the firewall (under cowl) at the back of the engine.

[Bozz80]

Not amped but not surprised that your post started with "So, this isn't going to be easy but..."

In my defense, I do know how to solder and use shrink tubing. I'm actually thinking about patching a fuse in line just to make sure this is easier to deal with if it happens again. I've already removed the cowl, removed the plate that the wiring harness box bolts to and loosened up the feeds in to the DME and at the other end of the wiring harness box.

I just got a new multimeter and and a cable finder toner.

My question really was whether I had to pull the intake manifold to pull the wire through. Your post indicates that I could just pull the burnt ones without pulling out everything. But the wires seem stuck below the massive loom at the bottom of the wiring harness box.

So what do you think, pull the manifold?

[Eric93se]

Not sure how your car is different but there are a bunch of hangers that the o2 wires latch on to. Its really important that they are used especially where they go past the exhaust manifold. You have to open up the long black box at the cowl, lots of wire in there.

[Stubikeman]

Hi, I just repaired the same issue on my 1998 E36 M3. The secondary O2 sensor wiring had touched the hot exhaust because the retaining clips were missing. The O2 sensor wiring for the Bank 2 secondary sensor burned, I'm guessing because of the electrical short all the way up into the wiring harness. I can confirm that it can be repaired. I just got my car to pass Smog here in California.
I had to go all the way into the wiring harness as under the windshield cowl to splice in new wires. I used some 20 gage wire from Amazon. I used crimp connectors but you could use solder and shrink tubing. Yes, I had to remove the intake manifold to get access to the wiring. It had also melted/burned some of the other wires coming into the harness so I had to replace those too. The hardest part was finding the part number for the O2 Sensor connector and pins, as mine had burned the wires all the way into the connector making it not reusable. I will try to find the part numbers if you need them.

[shogun]

The hardest part was finding the part number for the O2 Sensor connector and pins, as mine had burned the wires all the way into the connector making it not reusable. I will try to find the part numbers if you need them.
would be nice if you can post those part numbers for future reference

[Stubikeman]

Hi, I just repaired the same issue on my 1998 E36 M3. The secondary O2 sensor wiring had touched the hot exhaust because the retaining clips were missing. The O2 sensor wiring for the Bank 2 secondary sensor burned, I'm guessing because of the electrical short all the way up into the wiring harness. I can confirm that it can be repaired. I just got my car to pass Smog here in California.
I had to go all the way into the wiring harness as under the windshield cowl to splice in new wires. I used some 20 gage wire from Amazon. I used crimp connectors but you could use solder and shrink tubing. Yes, I had to remove the intake manifold to get access to the wiring. It had also melted/burned some of the other wires coming into the harness so I had to replace those too. The hardest part was finding the part number for the O2 Sensor connector and pins, as mine had burned the wires all the way into the connector making it not reusable. I will try to find the part numbers if you need them. Ok, so here are the part numbers I have, the male pin is 12521744077 you will need 4 of these and you might want to order an extra in case you mess up crimping one like i did. The housing is 12521427964. I reused the rubber grommets from the old connector.

[pbonsalb]

If you are driving through NH sometime soon, I might have some 02 harness ends from old harnesses. I had a short once that fried some wires in the tray and replaced the harness with a good used one.