Hi all,
Would a lazy post cat 02 sensor, bank2 cause this CEL fault? It's come on about 300miles since the last time I saw a CEL. At the time, I did not have an OBD2 reader, but I have one now and this is the code I saw. Both pre cat sensors have been changed, and when I looked at the data in real time, sensor2 bank2 is definately more sluggish.

cheers.

 

I belive that's the code when the cat fails, giving a bad sniff to the secondary sensor. Sometimes you can put an extension on the bung to fool the 02 sensor, works on a 996tt, not a 997tt(don't ask), so you should be fine. FVD makes a set fwiw.
Primary 02 sensors rarely go out or need replacing, usually secondaries(post-cat) are the issue. A failing primary would be indicative of a more serious, engine side issue. Your problem is most likely the cats imo.

 

My primary sensor failed. My info was that it gets hotter, so it fails first.

 

I agree,I think the primaries will fail more than secondaries if heat fatigue is the only issue. I was alluding to the root cause of the primary fail cel(valve guides, etc), I guess I didn't make that as clear as possible.
But p0430 and p0420 are secondary sensor bank 1-2 codes, usually cat, but not always.

 

In my original post, i mentioned that bank2 sensor2 was slow in comparison to the others. It was holding out at the lower voltage for much longer periods and the long term fuel trim for bank2 was +3%.....so my suspicion is the CAT is fine as the car has recently passed the UK emmisions test but the ECU is fooled into thinking that the CAT is bad due to the poor performance of the post cat o2sensor on bank2.

WRT replacement, should i go for a Bosch OEM part, a Bosch generic (which one), or an aftermarket?

cheers

 

Go with Bosch. 993 sensors "breathe" ambient air through the connector via the wiring. Sounds wacky but tis true. Eurocar parts for £100+VAT each or ~£75 each from http://www.pelicanparts.com/catalog/..._pg1.htm#item0 and take your chances on VAT and duty.

 

Check drivewire.com or driveline.com (can't remember what it's called). They're a generic parts house, but they have the correct Bosch OEM parts for our cars. Also try Pelican.