Hi guys!

I have a 1994 Corvette which has a bad o2 sensor wire harness on the right bank. I tested this by finding the voltage to be around 448 MV on Tuner Pro and after some research suspected the harness rather than the actual o2 sensor. Just to test I swapped my left bank o2 sensor with the right and sure enough no difference. I have tuner pro which tells me if it's ready or not... and it says it isn't and stays at the 448 MV. After inspecting the harness I found multiple frayed wires, I attempted to wrap with electrical tape but it didn't seem to make a difference.

I would like to replace the harness, I found them available online, just no real direction of where it feeds to before the ECM (I'm assuming?). Is this something I can just swap out plug and play or do I have to splice off the bad wires and replace from there?

I appreciate all help in advance, thank you!

 

Take a look at this: - He had to repair the wiring.

I had a similar problem, but my wires were fine, my connector was soaked with oil. I was able to fix mine (1995 Coupe) by cleaning the connector.

 

This helped a great deal thanks. I found my other end of the wiring harness disconnected and partially fried so yeah ill have to replace it. But I cannot seem to locate where it plugs into? I see the knock sensor location, I wonder if it's near there? I did remove the starter to see more access.

 

So to clarify, the RH Oxygen Sensor plug in is not connected to anything on the Passenger side.. I tried to locate a plug in but could not find it. It's near the knock sensor just like the image above is shown.

 

FYI

The o2 sensor wire, is not supposed to be soldered.

I used posi lock barrel screw crimps.

google it.

 

So I believe I discovered the culprit. Because I have long tube headers installed (sorry forgot to mention that) I only run two oxygen sensors. When I purchased the car off the last guy this was the latest thing he put in. I do not believe he put in heated oxygen sensors which is what I am researching now. I believe this may possibly not be putting the car in a closed loop but also could be because of those frayed wires.

 

To begin with, you won't have after-cat O2 sensors on a 94. Those only came on 96 C4s when they implemented full OBD2. Those after-cat sensors are only used to diagnose the function of the cats - they have nothing to do with how the engine actually runs. So you aren't missing any sensors.

You can check the circuits to/from each sensor all the way back to the PCM. Per the Factory Service Manual (see pic below) they are on the Clear or "C" plug (there are four big plugs that connect to the PCM, and this is one of them). The pins that go the left sensor are C19 and C20 and should be tan/white and purple/white respectively. Those are the wires that should be connecting to the driver's side sensor. The pins that go to the right sensor are C7 and C8 and they are tan and purple respectively (no white stripe). Those connect to the passenger-side sensor.



The O2 sensors should be heated, according to the manual (the "H" in HO2S stands for "heated"). You really need to get the correct ones for a 94 Corvette before you go any further. If the wires to the connector are frayed and/or you have to replace the connector, then I agree with dizwiz; you shouldn't solder them like the guy in the video did. Here's a thread that discusses that.

 

IHBDs, you are correct. Thanks for correcting that!