Cat sensor question

[Ogden325i]

Hello everyone I have a 1990 325i from Japan which is in need of a whole new exhaust system. I want to just get two straight pipes made and use a remus cat back. My problem is that there is a sensor attached to the old cat and when I delete the cat what do I do with it? What is this sensor and does it play an important role in engine management?
Thanks

[Adrian_Visser]

it's the O2 sensor. it isnt too hard to weld a bung on the new exhaust and tap it for the sensor. the O2 sensor fine adjusts the mixture once it (the sensor) is warmed up, to give better fuel economy. of course it doesn't work very well if it's old or contaminated by oil soot from your engine burning oil.

[Ogden325i]

So I have 2 O2 sensors?

[Adrian_Visser]

i don't know anything about jdm cars and i'm not sure motronic 1.3 would even support a second O2 sensor but e36's do have an O2 sensor if front of the Cat.

[Ogden325i]

So I took out the sensor and it looks to be a temp sensor so I'm not too worried about getting rid of it. Thanks

[Mako18]

What??? NO!!! You need that sensor, it plays a very important role in fueling among other information it provides to the ecu to change and adapt or calibrate. Bmw didn't put it there just to increase the build cost.

You should be able to pick up a decent stock exhaust pretty cheap. Unless you really want to use an aftermarket cat section they did a great job with the factory item. A catback like remus is a good choice but there are allot of other options search around.

[Ogden325i]

A new stock cat does not have any place to put this sensor, this is not the o2 sensor. It looks like it's a temperature probe. I ended up getting 2 2.25" pipes from the stock H pipe back to a magnaflow dual in dual out muffler. I just left the sensor out, car is running well except that it is a lot louder than I expected. I think I am going to put the magnaflow where the stock cat was and maybe get the supersprint as I saw somewhere on here that I can buy them in Canada. Back to the sensor, I called the stealer and they have no idea what it was for as their data base does not show any such thing even when he looked up jdm spec e30's.

[Liam]

That is a temperature sensor to detect catalyst overheating not an O2 sensor.