CEL Codes =- First P0421 and then P0421 and P0431

[ukroadster]

Hi All

Been using the forum for a while but first post :)

Ive had my 987 3.4s for 4 weeks now and its done 19k miles. It was serviced by an OPC just 1500 miles ago. Had my first CEL a couple of weeks ago. Went to an independent who read the code as P0421 cat warm up threshold problem (Bank 1).

He reset it and said see how you go as it may not come back. However 2 weeks later (last week) the CEL came on again. Went back to the independent who read the codes.

It now shows P0421 and P0431 so now both banks 1 and 2.

He has said that its the lambda sensors and suggests replacing all 4 which the dealer i bought it from is going to cover and then claim some back from the standard 3 month warranty he gave with the car.

Im just wandering though if this could be something further upstream, A MAF. Air leak or even possibly the catalytic converter failing ?

Surely a bit more diagnosing is needed rather than replacing the sensors that are indicating a fault ?

Did read that some 06 caymens had cats failing early.

Dont want the dealer to pay for 4 sensors now only for the problem to return and find its the cat on its way out. I guess he will then say that you can only make one claim under the 3 month warranty and he wont then pay out for a cat later.

Any thoughts appreciated ?

thanks

Andy

[Loren]

You need to look at the O2 readings before and after the cats to verify the cats are failing. That would be unusual unless someone put leaded gas(petrol) in the car.

They should also check for a valve error using a PIWIS tester.

I think this bears a more through investigation.