P0420 continued problems. Seeking desperate help / advice PLEASE.

[Wrinkly]

  On 9/22/2021 at 11:25 AM, Wrinkly said:

Jim

Have removed airbox as your suggestion, no obvious air leaks. I am assuming it is in order to lightly hear air passing along from the air cleaner when I have my ear on the delivery tube to the throttle body.

Regards and Best Wishes , John.

Still not able to find cause of P0420 code, despite all that has been done (as per above details in this topic). 

However the car has recently had, six of each, new Ignition Coils and Spark Plugs (all good manufacture, E.G. Denso) and Inlet gaskets were new ones of Jaguar origin. Is it possible that during re-fitting the Inlet Manifold, that a gasket has been pinched or not positioned correctly. The car is showing no signs of what is usually considered as typical Cat Converter in effective, E.G. Smell, low mpg. smoke, power loss etc. etc. Every time the code is read and reset it appears again in 18 -20 miles of use.

Cannot seem to be able to link this to previous posts on my topic and problem, sorry. Am now desperately seeking further help/advice please.

Further advice would really be appreciated.

Regards and Best Wishes, John