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P0431 (and P0421) codes CEL - lambda sensor part number check please

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First issue with my UK 2005 3.2S in 12+ years ownership, 45k miles on the odometer


CEL light on and codes P0431 stored with P0421 pending.  Had both these codes a few weeks back before clearing them and trying the best fuel quality plus Cataclean fuel treatment. 200 miles later the cel is back on with same codes.


MAF signals look fine, performance is fine but maybe the fuel economy is 5% down on normal.

Idles fine hot n cold and no obvious aural signs of exhaust leaks, albeit my stock exhaust has always sounded a little more fruity than the norm!


Local Porsche indie today confirmed the codes and tested the lambda sensors, one post cat converter sensor is a bit iffy but the other seems fine on short term analysis.


My first action I think is to change both post cat sensors, but I’m uncertain on part numbers, both Porsche and the equivalent Bosch items


I believe the original Porsche sensors were part 987 606 124 00,  but are maybe no longer available from Porsche??   Later cars used 987 606 123 02 I believe (also in the pre cat position) and I’m uncertain whether these are compatible ??



I’m trying to find the Bosch equivalents but online parts suppliers give conflicting data on which items fit my vehicle  - I think i am correct in saying


Bosch 0250 006 697  (possibly called LSF6697 in the USA)  is equivalent to 987 606 12400




Bosch 0258 006 810 (possibly called LSF6810 in the USA) is equivalent to 987 606 123 02


Can anyone verify the Porsche and Bosch parts numbers?



Possible not related but the fuel gas cap rubber seal is a little perished with some cracking, I’ve ordered a new cap, tether and rivet which will be fitted in a few days time. I'll check the oil filler cap just in case that's in a  similar state.


thanks in advance



Edited by percymon
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