Pre cats - again

[andyy]

Having all sorts of engine problems with my 500 so I thought I'd strip the top half down and have a poke around.
Removed the exhaust Y piece to make some space and noticed that both pre-cats were loose and wedged up against the lambda sensors.
Over time the cats had moved around whilst wedged against the sensors which had bent the ends of the cats flat.
The n/s cat was about 90% blocked and the o/s about 50%.
I've engineered the cats out completely but havent yet run the engine - I guess that having the exhaust almost totally blocked is not a good thing.
Maybe worth looking at if you're having running problems.
Cheers Andy

[starmist]

Quite common, I'm afraid. Could damage the Lambda sensors if left unchecked, which are around £100 each to replace.

No harm in removing them. They only control emissions when the engine is cold. Come MOT time, they always test on a warm engine, so no problem.