Shane

How does one splice in a new (used) shielded O2 sensor wire into the harness?

While putting Zelda back together, I put in a new O2 sensor in the Ott bypass pipe fed it through the grommet hole, then went topside to connect it up... Couldn't find the connector anywhere around the central electrical panel, until I noticed some plastic flex conduit wire-tied in place above the ground points. Opened it up to find the blue power wire to the O2 sensor heater was fried all the way into the harness...

I have replacement wire from a used harness to repair this, but not real sure about how to splice in the signal wire somewhere close to the LH Plug?

Lizard928

Just unplug the wire from another harness and replace the whole wire.....

SeanR

Agree with Colin, never a good idea to splice, just buy the correct one from pig-tale to O2

Shane

Can't as the spare harness I have is minus the LH and EZF plugs, so other than buying a new harness, what are my options?

M. Requin

Google "how to splice shielded wire". Skip the auto forums and look for the audio and electronics geeks. Commonly done, usually not hard (unless you run into shielding that requires silver solder or similar).

Shane

Thanks Martin, thats what I did, and in the process of prepping the wires started me thinking again...

Does the O2 power wire get its feed through the brain? And is it fused? If so where? If I fix the wiring what will keep it from frying again? Would a bad O2 heater fry the wiring all the way to the brain?

Lizard928

O2 heater power comes from fuel pump relay on the W plug.

None of the O2 wires I thought were shielded. Seem strange to have them shielded as they transfer voltage not a signal.....

docmirror

Ectually, the output signal of the O2 sensor is 200-800mV, so it is a low level signal. It also varies significantly in time, so having it shielded is a good idea in most any auto application. Stray EMF is prevented by a shielded cable, and splicing it is not really recommended, although it can be done carefully.

Shane

Found it! Took my wife up to the shop since she isn't color-blind and she pointed out the burnt blue wire coming out of the W-block and said, "Is that it?"

Does it take a special tool like the molex connectors to remove the female spade connector from the block?

dr bob

A dental pick or a heavy-duty needle works to depress the little locking tang. A hemostat is good to grab the back and manipulate it out while you fiddle with the tang. Helps to have three hands or a portable vise.

WallyP

The oxygen sensor operates by comparing the exhaust gas to outside air - the outside air wicks in thru the cable. Splicing might well screw that up...

GlenL

I tried to save a few bucks by splicing in a new O2 sensor and it seems to have been the root of engine management problems on my 944. Whether it's the "oxygen wicking" or just interference in a low-voltage signal, I had starting and running problems until I swapped out my "good" O2 sensor for a new, "real" one.

hernanca

I found the connector with the green wire to be quite brittle in my car (86.5). I can't help but believe others will find the same, and am wondering what the best solution is. We will eventually run out of spare green wires with (perhaps also brittle) connectors on them. I started a thread to discuss what the best solution may be (or whether we need to worry about it):
https://rennlist.com/forums/928-foru...l#post12765282