Need a little help trying to figure out what is going on. Recently bought a 2001 Corvette with Billy Boat exhaust. The passenger post-cat O2 sensor was not showing a voltage when I bought that car so I replaced both post-cat sensors (since the O2 sensors should be replaced in pairs). I ordered the stock sensors assuming that they would be adequate for the modified exhaust. I had to splice in the new sensors because the old sensors had a much longer lead on them and looked like they had been custom wired to the exhaust. Long story short, I spliced them in, soldered them up, and put them back in. However, when I run the OBDII scan while running the engine I am now getting codes P0141 and P0161 which is a heater malfunction on the post-cat sensors. The OBDII indicates that the voltage on both sensors is 0.45v. I checked the fuse and Fuse #15 is good.

At this point I don't know what to do. Are the sensors bad? Did I wire them up right? Does the custom exhaust mean that I should be using something other than the stock post-cat sensors? Anyone have any ideas on next steps?

 

Just an FYI - Bosch doesn't want you to solder the O2 wires. Reference air travels through the wires. Many will say they did it with no problem - flame on. I'm just telling you what I know from working at an OE and with Bosch directly.

 

So doing some research on tuning out the sensors it looks like that is no longer an option? The threads that I could find about tuning out the O2 sensors were back in '05 and '06. After that it appears the feds made it illegal to do that (which makes sense), especially here in CA.

 

If your code is a heater malfunction and not a catalyst efficiency, and the heater circuit is good, you most likely have them wired incorrectly. Did you compare the wiring diagram for the sensor to the wiring diagram for the car?
If you get catalyst efficiency codes with hi-flow or aftermarket cats and tuning them out is not an option, many times O2 spacers work.

 

I still have one some place in my shop that tunes them out along with every other code so you can pass your emissions tests

 

What model is that and how can I get one?

 

You have to find them used and unlocked. I don't use mine any more since I use Chuck Cow for my tuning needs

 

Are you interested in selling your?

 

yours...

 

I'm curious. If it's a heater circuit issue, that is not a tuning issue. Why would you be going down this path before fixing the circuit?

 

I'm pursuing both options in case the heater circuit fix doesn't work. That way if the wiring doesn't fix it then I will at least have a way to get the car back on the road (It's been down for almost 5 months now).

To that end, here is the chart that I used to determine how the wiring should go:

https://www.screencast.com/t/C1MdD5ay

The new O2 sensor is a Bosch and it has 2 white wires, a black wire and a grey wire. Although I am not sure, I believe the old sensor is a Denso sensor and it has 2 black wires, a white wire and a blue wire.

When I wired them up I wired the 2 black wires from the harness to the 2 white on the sensor (each one separate), the white on the harness to the grey on the sensor and the blue on the harness to the black on the sensor. According to the chart, that should work but it throws the heater codes.

So I know what the colors are for the new sensor. The question is how do I determine what is what on the harness so I can connect them right if the configuration I wired them up in doesn't work.

Also, does the fact that I get 0.45 volts steady when I check with my OBDII have any significance? I know that the O2 sensors are supposed to output voltage between .1 and .9 volts so the 0.45 seams reasonable but it doesn't appear to fluctuate like the upstream sensors. Prior to changing out the sensors I wasn't getting any voltage on one of them so I figured that getting some voltage on them should be good.

 

This would help if they were the original OEM sensors but with the modified Billy Boat exhaust, different sensors were put in than the OEM sensors. I know that for sure because the sensors between the drivers side and the passengers side were different with different wire colors.

Is there a way to test the wires on the harness to see what is connected to what?