Code P0420 - Cat or sensors?

markyp2000 wrote:

kirkynut wrote: Yes, a different MOT tester was telling me this recently - is this because there are no published specs for it Mark? So it has to fall back to those stats? That's what I've recently been told. A bit like the Mk1 Eunos Roadster I understand, Mazda never produced specs for that either - am I right?

With the new cat the emmisions did improve dramatically - however, I was somewhat confused by the EML not coming on and staying on, even after I cleared it, to tell me the emissions were out of range.

This could be the reason why - the range the emmissions are allowed to go to are alot higher than it was being tested to!

I have an MOT tester singing from the right song sheet now - so should be alright from now on!

Kirkynut

you dont have to tell me that as i am an mot tester

I know you are, I wasn't telling you, I was asking you if I am right in what I'm thinking, hence the questions ending with a question mark, Mark!

I guess you read it quickly eh?

Kirkynut

lol yer your right

Well didnt bother going to ShitFit. Googled them and heard too many horror stories echoing the ones in this thread.

So I have reset the code and put in some decent fuel and fuel cleaner (Wynns) and will see what happens.

Its not long had an MOT and it passed emmisions so its proably just the crappy T fuel that caused it.

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The catalyst needs to get hot to burn off any dirt, when mine wouldn't pass emissions we left the MOT artificial foot on it for 10 minutes @ 3000 rpm and it passed easily afterwards.
(I did keep sneaking a look at the temp gauge in case it overheated, but it was fine.)

Take it for a thrash down the motorway in dry weather.

I have to use petrol from the big T as they had a rather effective policy of buying up all the independents and closing them down so they could offer a price match within 2 miles on the pumps.
It is tiger petrol though...

Well having driven several hundred miles with the code reset, it has come back on again.

Since the last time I have only used premium non-supermarket fuel. But again, its come on during a long motorway run when p1ssing hard with rain. Could it be water or just the cold messing with the sensors?

I think it might be time to replace them...

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Just found this p0420.co.uk/p0420-catalytic-converter-ef...ow-threshold-bank-1/