Oxygen Sensor Replacement Questions
 

First, I want to say that I just got the 101 Projects book, and it's fantastic! I don't know why more repair books aren't written this way. The photos and writing style are fantastic and they build a lot of confidence. Thank you for writing the book!

My car is a 1996 4-door 328i. It is 100% stock.

I have to smog my car, and the Check Engine light is on. Your book says this probably means the O2 sensor. I'll try to take it to a shop to confirm - the brake pedal trick won't display engine codes.

I jacked up my car yesterday and looked for the O2 sensor. Are there two of them? The engine has two exhaust manifolds, one for the front 3, the other for the rear 3 cylinders, and it looks like there's an O2 sensor on each.

Your 96 is probably OBD-II so you need a code reader. Pelican sells a couple. Peake and Autoenginuity are two of them.

Your local parts store will read the codes for you.

You could have as many as 4 o2 sensors.

Your car has 4. Two are located in the exhaust manifold and the other two are located just past the cats.

Keith

Need to see what the ck eng light is 1st

Absolutely. No sense in replacing the sensors at $100 each if the CEL code doesn't indicate a bad sensor. On the other hand if it tells you that just one sensor is bad then replace both the ones in that position (before cat or after) or do all 4.