On Fri, 20 Sep 2019 16:37:43 +0100 (BST), "Dave Liquorice"
wrote:

On Fri, 20 Sep 2019 15:46:50 +0100, Scott wrote:

I *may* need to replace the catalytic converter in my 11 year old
Nissan Micra. I have seen some very good prices but also read that
aftermarket cats do not contain precious metals and do not last nearly
as long.

I know about running the car at high revs for 20 minutes to try to
clear the cat and so far this has been successful.

So why worry?

It's just contingency planning at this stage. My concern is that if
the cat fails catastrophically the car will not pass its MOT.

I've never heard of a catalytic convertors needing that treatment nor
of any engine managemnt system that tells you the catalytic convertor
has been killed.

P0420 code stands for “Catalyst System Efficiency Below Threshold
(Bank 1).” When you receive a P0420 code it means your catalytic
converter is not operating at maximum efficiency. Usually this means
your catalytic converter needs to be replaced or there is a problem
with your O2 (oxygen) sensors.
Source: https://exhaustsystemsguide.com/p0420-code/

They get killed by unburnt petrol or lead, your not
likely to notice untill the car fails the MOT emmisions test. But as
my last petrol car was about 15 years ago things in that world may
have moved on...

Yes, but what form does this morbidity take? Is it a case of the
passages becoming blocked or are the precious metals stripped away?

DPF's on the other hand do need the occasional "good run" to burn the
caputured muck out of them and the engine management system may
indicate when this is required. Normally only required if the car is
only used for short stop/start journeys.

Are you saying petrol cars do not require this?

Thanks