Yes, you need this part. It’s one of the most important tuning tools you can possibly have in your car, and is a big part of keeping the engine safe.
-If you have a 4-wire sensor (1.8L cars) you’re going to use the BLUE wire on your engine harness, that’s the o2 sensor signal wire. I have reports that the rest can be capped off without any check engine lights.
-If you have an OBDII car (1996+) you’re going to replace the FRONT sensor, not the one after the catalytic converter.
-If you have pre-sensor exhaust leaks, it will read very lean and actually add extra fuel, causing a rich condition especially at idle. Fix your leaks!