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1997 528i

1K views 3 replies 3 participants last post by  shonessmonster 
#1 ·
I know this is a very rookie qustion but I just recently failed smog and needed to change my O2 sensor. I was notified that normal automobile has 2-4 O2 sensors and now I need to know how many my car has, so I can go online and get however much needed.

Thanks.
 
#2 ·
There's four. Two before and two after the catalytic converters. The codes that indicated failed O2 sensors will also indicate which one(s) failed. They have a "book" life of 100k miles; I'd replace them in pairs. The two before cat are probably your best bet if you're guessing. After cat take longer to fail.
 
#3 ·
I'd replace them in pairs
I've never done oxygen sensors so, to the OP, keep us informed how you handle this (pics are always nice).

I found my oxygen sensors simply by posting a picture of where I "thought" they were and people here showed me in my picture where they were.

Dig around in the VERY best of E39 Links as it's a very common subject.

Do a browser find (control f) for "o2" or "oxygen" and you'll see tons of links, e.g.,
- Oxygen sensor DIY (540 M62) (525 M54) & O2 sensor tools you can make at home (1) & all about 02 sensors (1) & eliminating the rear o2 sensors (1)

PS: In most states, Autozone will lend you the tools for free.
 
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