I'm trying to relocate my secondary o2 sensor past the second catalytic converter (now my only cat) after installing an OBX header, downpipe, and SR*S catback. I've got the bung ready to go, but the wiring on the sensor isn't long enough to reach past the cat, and there isn't enough slack under the dash to make up the 4-6 inches I need to reach the new location (at the end of the cat, or beginning of catback). I know that the black wires are heater wires, and I'm pretty sure you can't just cut and splice extensions onto these...or can you?

Any advice on modding the existing sensor wiring would be appreciated, or even some direction to a replacement with longer wiring (will buying a second header o2 sensor work? I think those wires are longer...not sure if it's the same connector).

Right now I took out the sensor and plugged the bung so I have something to compare...

I don't want to eliminate the sensor as I'm sure some emissions shop is going to bust me for removing it and putting in a cheat simulator...

 

You can splice the wires without a problem. Just make sure you have a good connection and that it's sealed to prevent corrosion. Some 02 sensors are vented to atmospheric O2 content through the wiring harness insulation but ours are not.

Remember that we are dealing with very low voltages and that a good electrical connection is essential to prevent a voltage drop across the splice.

 

Do you recommend using connectors or soldering? What's the best insulation tape to use for the wiring exposed under the car?

 

You can use butt splices no problem. Just make sure to seal the connection with heatshrink tubing. I suggest you run the wiring through some fiber or plastic cable wrap, but even without it you should get several years of trouble free service out of the wiring.

 

Cool, I grabbed some heat shield tape...supposedly works up to 300 degrees, so that should be fine as the wiring won't be too close to the exhaust.

Thanks for the input. Glad it's not as much of a PITA as I was fearing.

 

why put the second O2 past the Second cat? You will throw a CEL for sure.

 

^^^Because I eliminated the first cat. I shouldn't have a problem with the CEL going off as long as the engine reads that the emissions are up to par. The original placement only read it after the first cat, not after both...so as long as one cat is in between the sensors it should be fine.

 

it still might throw a CEL, like O2 bank2 slow responds or O2 bank1 slow responds, the O2 has to heat up properly in set time. Will heat up slowly cuz it's further back which in turnstill throw a code. the Ecu will be looking for both sensors, unless you have some type of ecu rom recoding like the EVO drivers.

 

interesting. Well, we'll see if it will get me past getting a sticker. If it throws a CEL in the future, I'll probably just grab one of those emulators off of ebay and see if that will take care of it...

 

Cool, so far so good. Extended the wiring, used heat-shrink connectors, used heat shielding, and connected it past the cat on the upper part of the pipe to avoid moisture damage. 40 miles so far on the reset CEL and haven't thrown it yet...I'll keep you posted...

 

You should be good to go. I had the same problem. I got aftermarket headers with no cat and a downpipe that took out my second cat. So I got a magnaflow high flow cat put in and had to move my o2 sensor further down. I just cut the wires, used electrical connectors to extend it, and electrical taped it up and made sure it wasn't hanging low and it's been good for about 5000 miles.

 

cool...it's already running better. Reset the tranny last night to maximize the performance end of it, definitely more aggressive when passing on the highway.

As for hanging low, that little twisty connector on the floor board definitely came in handy