Thanks everyone for your thoughts, I am delighted to say the Gold Star goes to….Doug!
Just removed my cat and one core is intact, the second had broken down and was firmly wedged into the exit forming a nice plug.
New one ordered, may use the Omex log approach to work out why it degraded after just 20k miles…
Thanks again everyone!
Great news
However, as you rightly say, why it degraded after just 20k miles is the important question here?
If the engine has been running excessively rich the unburnt fuel will have built up in the cat, and when that fuel lights off it'll create a rather effective kiln which will soon break down a cat matrix, I've seen catalytic converters glowing cherry red when this happens.
The Omex logging feature will help you confirm or deny an excessively rich condition
'lambda feedback', it'll also immediately show if your lambda sensor itself is working? Keep in mind an excessively rich condition will quickly contaminate a lambda sensor leaving the ECU to fall back on the open loop fuel table, which itself may have been calibrated on the rich side.
Also, check the
'fuel cut on overrun' feature is active, typically this is only active above 2,000rpm to avoid drivability issues, but if its never been activated at all you can end up flooding your cat when you lift off the throttle, especially if the fuel table has been calibrated on the rich side in the decel/low load cells.
It's definitely worth spending some time investigating the route cause of the issue, and before you cook another expensive cat
