Firstly it may be inportant to say this is a UK spec car, Engine code ASN.
I have a reacuring (every three weeks or so ) po431 fault code. I know and except that this points to a cat problem on bank 2 but whilst trying to investigate the problem I have some strange o2 sensor wave form rsults (useing VCDS (VAG,COM)). The software is working correctly as I have tested on other cars but results on my car are odd.
On bank 1 Both pre cat and post cat sensors read very little fluctuation and hover arround the .6v area.
On bank 2 Both pre cat and post cat sensors read lots of switching fluctuating between .2 and .8V.
No O2 sensor fault codes are recorded on the vehicle, the only code when scanned is the P0431.
I was expecting lots of switching of the pre cat sensors and more settled on the post cat sensors on both banks, with bank 2 post cat sensor probably showing more switching because of the failing cat on that side.
To sum up, What I need is to know which PRE cat sensor is reading correctly? and are Wideband sensors fitted to this vehicle. Maybe this would explain the flat, pre cat readings on bank 1.
Cheers
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Monday, September 27th, 2010 AT 8:24 AM
