Catalyst system fault - o2 sensor?

**thor_wulff** · 15-09-2009,12:19 AM

Hi I have scaned and found two fault codes - i have cleared them but they return within a day or so, first i only had bank 1 then a couple of weeks later bank 2 also.

(its a n A4 2.4 V6 year 2000)

16804/P0420/001056 - Catalyst System; Bank 1: Efficiency Below Threshold
16814/P0430/001072 - Catalyst System; Bank 2: Efficiency Below Threshold

has any got an idea if this could still be related to the sensors ? CAT's? - is it not strange that both sensors would fail at the same time? or does this indicate that there is another problem somewhere else? as always any help or suggestions much appriciated!

I have done a readiness test and the result is below...could it "just be the o2 sensor"?

d

**thor_wulff** · 16-09-2009,12:45 AM

it passed MOT emmison test with no problems....?

**VAGMAN54** · 16-09-2009,06:03 AM

you need to check the rear lambdas are working

**thor_wulff** · 16-09-2009,11:31 AM

the lambda - is the O2 sensor right? - can it be checked vith vagcom? or it there a simple way to test it??

**VAGMAN54** · 16-09-2009,07:47 PM

yes vag.com it i carnt remember the numbers but if you have a label file it will tell you in there ,the rear should be as close to 0.00 as possible it will never be that good but should be somewhere close what was the fault code ?

**thor_wulff** · 16-09-2009,11:26 PM

the fault codes where

16804/P0420/001056 - Catalyst System; Bank 1: Efficiency Below Threshold
16814/P0430/001072 - Catalyst System; Bank 2: Efficiency Below Threshold

when i ran a readiness test on the engine it came up with "FAILED" under certain elements (see screenshot in begining of post)

**thor_wulff** · 17-09-2009,10:20 AM

might be a stupid question but what do you mean with "label file"? - should i have one? /where do i get one?

**VAGMAN54** · 17-09-2009,08:22 PM

label file is at the top of the screen when you have gone into engine,measuring blocks...it will be on top of the screen and those codes mean the cat aint working properly so i would check those rear lambdas first