02 sensor questions

[Triki]

Fitted a decat to my car yesterday, eml came on straight away once warm and i didnt like how loud it was......
So today i have swapped the cat back on the car cleared the codes, which came up as bank 1 oxy sensor. Got it up to temp and the eml is back on.

Are oxy sensors for a 182 the same pre and post cat ?

I have read a few things about people swapping sensors round, does this work, or do i need to get my wallet out ?

Seems strange it should still be coming on, but i have read that people have had this issue before after swapping from a de-cat back to a cat.

 

[Jonny1*2]

Sooooo many threads on this mate. If you had done a search for "Lambda" you would have found it in no time Pre CAT sensor is the main sensor. Post CAT doesn't do anything, although if you fit a decat to it you'll get the management light on due to it thinking there is a problem. It will have not effect on the car though.

 

[Triki]

I did search, but the results came back with many conflicting opinions. I suspect from people "Who think they know" as opposed to people who know.

I know which sensor does what, and what it does. Was just after some firm answer that swapping the 2x sensors was a viable option. Which i have now done anyway.
And i was struggling to get my head round why after fitting a decat, there should be a problem with the pre cat sensor ? Post cat, obviously due to the decat. But pre cat should be no different imo.

 

[shumoboi]

you would think but the rear lambda sensor is there for a reason, although it is just a referance sensor on this model it interpretates information about the oxygen and fuel content in the exhaust after the exhaust gas has been passed throught the cat, if the fuel or oxygen content after the cat is too rich or too lean then this information is sent back to the ecu and the fuel/air mixture is adjusted accordingly. as in your case there was no cat fitted then the fuel mixture is far more rich than having a cat in place, because you have no cat the rear lambda is now trying too operate in an alien environment and as the fuel mixture is far more rich the front lamda will send this information to the ecu to adjust injection frequency to try and lean out the fuel mixture but because there is no set "mapping" for this then the ecu will flag up a front lambda "sensor malfuction fault" .