CONTINUATION OF P0420 CODE PROBLEMS.

[Wrinkly]

There are numerous submissions on this section regarding the long time it took to get to the bottom (so I thought) of my P0420 codes and problems.

In brief, July last year (61847 mls) Full service (all filters new) and Inlet Manifold removed to fit new manifold gaskets (6x Jaguar original)., 6x New Ignition Coils (Denso as original), 6x New spark plugs (NGK0, 2 New Lambda Sensors (Up and Down Stream. Denso, as Original), New Catalytic Converter. The car had been misfiring and I believe it killed the existing Cat Conv, (which had disintegrated internally).

Since then to date (09.06.2022) car has travelled 4,233 miles (66080). During that time I have had on three occasions a P0420 code arise. The third being yesterday. Each time before, I had checked all joints in air intake system from filter to manifold with no leaks detectable. MAT has been checked and is OK. When code is cleared the car is A1 for about 400/500 mls and then the code reappears, as it did yesterday. Have not yet removed the code on this occasion. 

Being as every thing was NEW and to OE Specification can anyone offer an explanation or advice on why this code, all be it very intermittently, keeps reoccurring ?                                               All of this is obviously subject to Bank 1. Never had any problems with Bank 2.

Best Wishes and Regards, John

[Wrinkly]

Further question in the pursuit of exploring my above problem.

Have to day managed to get live  % readings from Upstream and Downstream Lambdas (both of which were NEW Denso stock as per original, less than 12 months and 4000 miles ago). This is all Bank 1 related, not that it matters. Downstream is very near on static reading .... between 0.07 - 0.09 %. Upstream fluctuated much more ....... 0.06 - 0.124 %. 

Question : Should there be this difference in readings or should they both be very similar and reasonably static ?

Any further advice or suggestions would gratefully received .

Many Thanks and Regards, John

[Wrinkly]

On 6/12/2022 at 8:33 PM, Wrinkly said:

Further question in the pursuit of exploring my above problem.

Have to day managed to get live  % readings from Upstream and Downstream Lambdas (both of which were NEW Denso stock as per original, less than 12 months and 4000 miles ago). This is all Bank 1 related, not that it matters. Downstream is very near on static reading .... between 0.07 - 0.09 %. Upstream fluctuated much more ....... 0.06 - 0.124 %. 

Question : Should there be this difference in readings or should they both be very similar and reasonably static ?

Any further advice or suggestions would gratefully received .

Many Thanks and Regards, John

This reading was taken with an iCarsoft CR PRO and showed a percentage reading. Is any other form of test available using this new Diagnostic unit ?

Many thanks, John