UK-POLOS.NET - THE VW Polo Forum

Hi I fitted a catalytic converter to my 1.4 6N2 about two years ago, it has always had problems with emissions at MOT, but in the past fiddling with Oxygen sensors has cured it enough to get through the test. This MOT it failed again and when I took the cat off to have a look at it there was no core, you can see you right through it. Although definitely had a core when I installed it two years ago. Engine warning light has been on for some time.Sny ideas?

Was it a cheap cat? Sometimes the break down and itll all come out the exhaust. Genuine is the only way to go on these

Engine warning light is probably due to the post cat lambda detecting bad values due to no core.

That’s useful thank you! It was the only manifold cat Eurocarparts offered at the time over £200 I’m sure. Pre manifold oxygen sensor was replaced a couple of years ago but the rear one was on the car when I got it nearly 5 years ago, seems a pretty good idea to replace that as you suggested along with a new (decent) cat. All other exhaust less than a year old but I put the old rear oxygen sensor back in when I did that. Very grateful for your help I will let you know how I get on.

When I got the old cat off the car I noticed that the front lambda sensor and the exhaust pipe leading down from the cat where very sooty and black. Could this have anything to do with the failure of the cat?

That would imply over fuelling. Too much fuel can make the cat excessively hot. On a cheap cat it could cause breakdown of the material inside

alexperkins wrote:That would imply over fuelling. Too much fuel can make the cat excessively hot. On a cheap cat it could cause breakdown of the material inside

I’ve got a cat and oxygen sensor going if you still need one.


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