I have followed the How To on here to move the lambdas behind the main Cats to elliminate the 0420/0430 fault codes.

I couldn't get the original lambdas to budge so, rather than damage them, I disconnected them but left them in place.  I then sourced a second-hand set of replacement lambdas (from the 3.2 that Albs has been breaking) and fitted them about 2 weeks ago.

Since then, no further issues with 0420/0430    However, lots of instances of the following codes popping up: 

P0136 O2 Sensor circuit High Voltage (Bank 1 Sensor 2)
P0156 O2 sensor circuit slow response (Bank 2 Sensor 2)
P0156 O2 sensor circuit malfunction (Bank 2 Sensor 2)

I'm led to believe that the lambdas very rarely fail, but these codes indicate to me that is all is not well...

Can anyone suggest anything that could be causing this other than faulty lambdas, because I'm loathed to spend £160 on 2 new genuine GM lambdas, if they are not at fault...

TIA 

Kevin Wood wrote on 06. May 2011 at 13:46:


Hi Kevin,

Unfortunately I don't know anyone in my area with a tech2 or similar (I have asked on here a couple of times previously).  Short of waiting for another meet, I'm a bit stumped on that one. 

Marks DTM Calib wrote on 06. May 2011 at 16:53:


As far as I can tell, yes.  I used the connectors that are mounted either side of the transmission tunnel, just aft of the gearbox...