jamieM

hi all, cars in for mot tommorow i been having intermitant cel, code p0420 so we will see if it passes. if it does pass, do you think that anti foulers will keep the cel away with the standard cat thanks

jimboturbo

Mine would not pass without the cat in last week. diddn;t need antifowlers in the cat tho?

SiDHEaD

Mine failed by loads so i took it to a better garage Although mine has a testpipe

MB

Jamie,

Im confused. Do you have a standard cat or a decat?

If its a standard cat then antifowlers will make no odds as the MOT uses their own oxygen sensor.

jamieM

hi mark, yes its standard cat, but i was wondering if anti foulers on the standard cat would keep the cel away

MB

If you have a genuine CEL then you dont want to be hiding it by any means of jiggery pokery.

The fault is generated when the secondary sensor decides things are a bit rich.

You need to find out what is causing it.

More than likely your cat is buggered and it would fail on emissions, rather than just having the CEL on the dash...

jimboturbo

Yes.. if you have a CEL with a cat in get it checked out..

jamieM

hi mark. it passed the mot so i am getting the cat code all the time p0420 so what can it be? man at mot place said emmisions were fine, what now?

MB

Id then suspect your secondary sensor may be playing up if it passed ok.

Not much I can advise over the net on that, is it will need a diagnostic to plug in to see its voltage.

I will do some digging though...

jamieM

yes its a strange one alright, thanks for that.