2nd 02 sensor in Downpipe?

[Well Whoop De Do]

I currently have the stock downpipe on my S14 KAT. I bought a blitz downpipe. I does not have a hole for the sensor that is on the stock one. It hooks in right before the cat. What does this sensor do and is it necessary? If it is I can just get someone to weld it in. Just wondering...

[daniel240]

you should keep the first sensor. the 2nd sensor is suppose to be after your cat. if you dont have a cat then there is no need for the sensor. it basically is there to make sure the cat is working properly.

[klattr1]

anyone know how to trick the ecu if you left out that second 02 sensor?like what resistor i could use so i dont get an unwanted CEL?

[Well Whoop De Do]

So in the downpipe (stock) there is a cat?

So I can just unhook it and the car will work fine?

[klattr1]

i left mine unhooked and the car runs fine but it throws a Check Engine Light code. Its just used for diagnostic purposes, so yes you can leave it unplugged. The engine does not operate off that 02 sensor.

[Well Whoop De Do]

Ok! That will save me a lot of $$$ then.

I don't care about the check engine light since I took it out when I did the transmission swap.