Hey Everyone,

I picked up a 95 OBD I 3.9 v8i a month ago and now slowly working on getting it back to road-legal status (sits as non-op). One of the things on the to-do list is putting new O2 sensors in. PO had previously removed both cats (I had a new pair welded on) and noticed only a RH passenger side sensor was connected. I ordered two new ones thinking the driver side just needed to be hooked up, but upon further inspection, i'm having trouble finding the connector end that plugs into the cabling on the LH Driver side.

I took a few pictures of how the wiring situation looks—has this been modified in any way? Tried looking it up on the RAVE manual but couldn't find much detailed info on the wiring layout.




Appreciate all and any help. Thanks!

 

Okay I took a closer look and it appears it has been messed with and that there are missing wires on those 3 LH driver blue connectors—i assume thats where the O2 sensor connector goes, correct?

 

Yes, correct. Original connectors were plug-in style that tucked down behind the engine. The black wires are not original wiring. I think I see the round, three-wire plug in the background of the first photo, RH side.

 

Thank you for the info John. Am I wrong to think this could potentially be a simple fix by sourcing a pigtail with that exact round plug for the LH o2 sensor and splicing it onto those existing blue connectors?

Here's a closer photo of the RH connector with a few labels:

 

It looks like the two O2 sensors are connected together by the black wires. That is no bueno. The ECM works on each bank separately to control fuel trims so tying them together could cause problems for both banks. Each O2 should wire to their own terminals on the ECM and if they are crossed, one bank could go full rich and the other full lean. Do you have the CEL on? Any codes showing?

 

Yes, I do have the CEL on—code is showing 44 (left o2 sensor).

 

With that wiring, could be code 45 (right lambda sensor) is also active. Do you know how to clear the code to check? If not, check out JE Robison Service, Retrieving Fault Codes, for code list and descriptions, plus steps to clear.