The check engine light came on last night so I did a quick scan and it came up with this:

VAG-COM Version: Release 409.1-US

Control Module Part Number: 030 906 032 CG

Component and/or Version: ME7.5.10 3622

Software Coding: 00031

Work Shop Code: WSC 00788

1 Fault Found:

16804 - Catalyst System: Bank 1: Efficiency Below Threshold

P0420 - 35-00 - -

I cleared the code and restarted and took the car for a drive, and nothing came back up, but this has happened a couple of times, last time I had the following, which disappeared after clearing it:

VAG-COM Version: Release 409.1-US

Chassis Type: 6N - VW Polo

Scan: 01,02,03,08,15,17,19,25,35,41,45,46,55

-------------------------------------------------------------------------------

Address 01: Engine

Controller: 030 906 032 CG

Component: ME7.5.10 3622

Coding: 00031

Shop #: WSC 00788

4 Faults Found:

16514 - Oxygen (Lambda) Sensor B1 S1: Malfunction in Circuit

P0130 - 35-00 - -

16804 - Shareware Version. To Decode all DTCs

P0420 - 35-00 - Please Register/Activate

18010 - Shareware Version. To Decode all DTCs

P1602 - 35-10 - Please Register/Activate - Intermittent

16519 - Oxygen (Lambda) Sensor B1 S1: Heating Circuit Malfunction

P0135 - 35-10 - - - Intermittent

Readiness: 0000 0000

Anyone have any ideas, obviously it's picking stuff up from the exhaust, the 2nd log is clearly the lambda snesor, but what is the 1st log about?

Also, if I clear them and they don't come back, does this mean there is no fault, maybe just a glitch?

I'm sure the first one is also oxygen sensor related ? Because that same thing came up on my car and i wasn't sure what it ment, so I started on the cheapest exhaust component (pre cat oxygen sensor) and I then fitted it, cleared code again and 13months later, still nothing has came back.

Ah right excellent, if it comes back, I'll get it changed. Is there another lamdba sensor on the 1.4 8v engine, do you know?

Ah right excellent, if it comes back, I'll get it changed. Is there another lamdba sensor on the 1.4 8v engine, do you know?

From the ECU part number it looks like you have the AUD code engine?? (1.4 8v) if so there are two lambda sensors before and after the CAT

Yep I have the AUD engine!

Is there any way of finding out which one may be faulty rather than replacing them both, or is it good to replace both at the same time?

Yep I have the AUD engine!

Is there any way of finding out which one may be faulty rather than replacing them both, or is it good to replace both at the same time?

From your Vagcom print out it shows "Bank 1 Sensor 1" this is the "pre-CAT sensor" the one in the manifold

Excellent, thanks very much. The check engine light came back on today aswell so I'll get a o2 sensor ordered up for it and hope for the best!

Does anyone know if there is a way to test the O2 sensor? Also, is it best to use a sensor direct from VW or will a bosch one do just as good job? (I imagine they probably use Bosch ones anyway?)

If it turns out not to be the O2 sensor, am I then looking at the catalytic converter? How much are these from VW? As I've heard that non OEM cat's will throw a fault up on the CEL?

yeah they use Bosch anyway. The cat wouldnt necessarly throw a code up. Just check your wiring before you buy a lambda sensor as they aint cheap! What did the code come back up with?

and you can test your lambda using vag com too

It came back with the catalyst system bank 1 efficiency below threshold. Ye, they are a bit pricey, but on eurocarparts using the 25% discount from the forum, it brings the bosch one down to about £72, so not as bad.

I haven't got the full version of vagcom, just the shareware so I don't think I can do tests on specific components, just read/clear faults

It came back with the catalyst system bank 1 efficiency below threshold. Ye, they are a bit pricey, but on eurocarparts using the 25% discount from the forum, it brings the bosch one down to about £72, so not as bad.

I haven't got the full version of vagcom, just the shareware so I don't think I can do tests on specific components, just read/clear faults

its not you lambda sensors ,the sensors are picking up your catylst is faulty you new need a new cat and both sensors

I thought if the Cat had gone bad, that it would produce sulphur dioxide, causing a rotten egg smell?

Also, if it was the O2 sensor, wouldn't it be the one at the rear, not the pre-cat one? Because it compares readings from both sensors to figure out if the cat is faulty?

The fault code you put up shows it to be the first sensor in the manifold (bank 1 sensor1)

Cheers nige, I'll replace the sensor in the manifold before going down the cat route as its the cheaper option, This car has been a nightmare recently!

Oh ye, I just did a readiness check and it came up as all passed?