I need to replace the oxygen sensors on my BMW 33i conv. Which sensors do I need? The ones for before or after the catalytic converter and how many doI need?

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This post was auto-generated based upon a question asked on our tech article page here: Pelican Technical Article: Replacing your 3-Series E30 Oxygen (Lambda) Sensor

It depends on the codes you have. If you have codes for the pre-O2 sensors then replace the ones before the cats. Remember just because you have an O2 sensor code does not mean the O2 sensors are bad. Vacuum leak, low fuel pressure and dirty MAFs can cause these codes.

- Nick