Engine Fault Code Catalyst System Bank 1 - WHat does it mea

[davedougan]

Hi, I have a 3-cyl 1.2 2003 Polo which keeps showing the engine warning light (the orange picture of an engine). I keep clearing it every couple of weeks using VAG-Com. However it keeps returning. Anyone know how to cure it permanently - do I just have to replace the Exhaust sensor blow the exhaust manifold? The code is shown below.

2 Faults Found:
16804 - Catalyst System: Bank 1: Efficiency Below Threshold
P0420 - 35-00 - -
16556 - Shareware Version. To Decode all DTCs
P0172 - 35-10 - Please Register/Activate - Intermittent

cheers

David

[alexperkins]

Sounds like the mixture is running rich. A lambda sensor may well be up the creek.