Just yesterday I replaced the down stream 02 sensor on my 2006 Volvo S60 and the car seems like it lacks power and feels sluggish staying at a constant speed. I’ve read that I’m supposed to reset the ECM by removing the negative cable from the battery for 1-2 minutes and drive the car for about 50 miles. Well I’ve done that and it hasn’t made a difference at all. Is the o2 sensor the problem??? Any help would be greatly appreciated!

 

Why did you replace the rear oxygen sensor?

It's only job is to verify the converter is working - and has no and can't have any effect on how the engine performs.

 

[QUOTE=hoonk;510354]Why did you replace the rear oxygen sensor?

Ended up getting rid of the cat because of it being clogged and I didn’t have a place for the o2 sensor so I tied it off. Came undone and it got beat up by the concrete. I was having problems with it running to rich after all that so I thought a new down stream would solve the problem.

 

The cat could have "clogged" because it melted - due to overheating from too much fuel in it - so it may have been running rich (or misfiring) for a long time.