# 16804 - Catalyst System; Bank 1: Efficiency Below Threshold



## Cody2003 (May 19, 2009)

Hello I recently got this code and while trying to diagnose it I came across a few issues. First I noticed that while running the test for block 034 the aging value was around .755. I was reading that it should at least be .80+. Also while trying to run the test on block 046 I could not get it to initiate. There were a few times when it would say Test On then after about a second it would say Test Off. I am just wondering if the pre-cat O2 sensor is good and how to get the block 046 test to run correctly. 

16804 - Catalyst System; Bank 1: Efficiency Below Threshold 
P0420 - 35-10 - - - Intermittent
Readiness: 0000 0000

I have been reading around and from what I have gather it is most likely the Cat. I have been hearing the exhaust rattle at low rpms for a while. While getting some of my exhaust done I had checked for rattles and did not find any. I heard this could be the inside of the Cat going bad?

Thanks for any and all help.


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## Uwe (Jan 16, 2000)

http://wiki.ross-tech.com/wiki/index.php/16804/P0420/001056

-Uwe-


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## Cody2003 (May 19, 2009)

Thanks for the link. That’s basically where my search began. I have searched Google and vwvortex to find out how to do the tests just cannot seem to find out why I cannot do the block 046 test. I performed block 034 test, then got the cat above 400C, in basic settings mode, pressed and held brake, pressed and held accelerator to WOT. It just seems to not want to initiate the block 046 test and I cannot figure out why. I really would like to narrow down the issue to a special sensor or if it is in fact the cat, instead of throwing money and it and hoping I bought the right part. 

I am going to get under the car tomorrow and check for any possible leaks as well as check the intake for leaks just to cover the basics.


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## Dana @ Ross-Tech (Sep 15, 2009)

If this is the 2003 1.8T the 046 test should run after all of the other self tests have passed. Meaning, 034 followed by 046 may not test on and complete successfully.

You should have a readiness script in our current release if you're using a Ross-Tech intelligent interface. Post the actual scan data from this car. If its stock (not tuned) you may have an update programming available at the VW dealer that might resolve Catalyst Inefficiency faults.


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## Cody2003 (May 19, 2009)

Here is the initial scan I got on the 2nd.

Wednesday,02,February,2011,16:29:46:45595
VCDS Version: Release 10.6.3
Data version: 20101206



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


Chassis Type: 1J - VW Golf/Bora IV
Scan: 01 02 03 08 15 16 17 19 22 29 35 36 37 39 46 47 55 56 57 75
76

VIN: 9BWDE61J634006417 Mileage: 207520km/128946miles
-------------------------------------------------------------------------------
Address 01: Engine Labels: 06A-906-032-AWP.lbl
Part No: 06A 906 032 LP
Component: 1.8L R4/5VT G 0005 
Coding: 07500
Shop #: WSC 00000 
VCID: 77F31C827F4B
9BWDE61J634006417 VWZ7Z0B5342566

2 Faults Found:
16840 - EVAP System: Very Small Leak Detected 
P0456 - 35-00 - - 
16804 - Catalyst System; Bank 1: Efficiency Below Threshold 
P0420 - 35-10 - - - Intermittent
Readiness: 0000 0000

-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 1C0-907-37x-ASR.lbl
Part No: 1C0 907 379 K
Component: ASR FRONT MK60 0103 
Coding: 0021505
Shop #: WSC 00000 785 00200
VCID: 3265ED96D4A9

No fault code found.

-------------------------------------------------------------------------------
Address 15: Airbags Labels: 6Q0-909-605-VW5.lbl
Part No: 1C0 909 605 F
Component: 08 AIRBAG VW61 0202 0001 
Coding: 12344
Shop #: WSC 00000 
VCID: 27530CC2EF6B

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments Labels: 1J0-920-xx5-17.lbl
Part No: 1J0 920 906 J
Component: KOMBI+WEGFAHRSP VDO V07 
Coding: 07232
Shop #: WSC 00000 
VCID: 2F63E4E2C79B
9BWDE61J634006417 VWZ7Z0B5342566

1 Fault Found:
01304 - Radio 
49-00 - No Communications

-------------------------------------------------------------------------------
Address 19: CAN Gateway Labels: 6N0-909-901-19.lbl
Part No: 6N0 909 901 
Component: Gateway KCAN 0001 
Coding: 00006
Shop #: WSC 00000 
VCID: F0E1A79E9A25

1 Fault Found:
01304 - Radio 
49-00 - No Communications

-------------------------------------------------------------------------------
Address 46: Central Conv. Labels: 1C0-959-799.lbl
Part No: 1C0 959 799 C
Component: 1J Komfortgerát HLO 0003 
Coding: 00064
Shop #: WSC 00000 
VCID: 3773DC823FCB

Part No: 1C1959801A
Component: 1J Tõrsteuer.FS KLO 0002 

Part No: 1C1959802A
Component: 1J Tõrsteuer.BF KLO 0002 

No fault code found.

End ---------------------------------------------------------------------


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## vwemporium (May 27, 2002)

::::: WARNING EMERGENCY FORUM ACTION MESSAGE:::::

THIS POST VACATED BY JACK TO PROTECT CONTENT FROM FALLING INTO THE GAPING HOLE OF THE VORTEX! 

THIS SOLAR SYSTEM IS IN DANGER OF A BLACK-HOLE!
YOU TO CAN ESCAPE!
I CAN BE FOUND VIA THIS DHD STAR-GATE ADDRESS......
http://forums.ross-tech.com/member.p...European_Parts


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## Cody2003 (May 19, 2009)

So the I get the firmware update at the Dealer I take it? I replaced the n80 in September and passed smog in October. My readings for smog were about average which is why I am hesitant to replace the cat. But.. it is probably the better place to start because if it is clogged it wouldn't be to good to continue driving with it. I ran the tests on the MAF and it was within spec, also cleaned it a month ago. The EVAP leak it something I am going to work on next weekend.

Thanks for the help and information.


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## vwemporium (May 27, 2002)

::::: WARNING EMERGENCY FORUM ACTION MESSAGE:::::

THIS POST VACATED BY JACK TO PROTECT CONTENT FROM FALLING INTO THE GAPING HOLE OF THE VORTEX! 

THIS SOLAR SYSTEM IS IN DANGER OF A BLACK-HOLE!
YOU TO CAN ESCAPE!
I CAN BE FOUND VIA THIS DHD STAR-GATE ADDRESS......
http://forums.ross-tech.com/member.p...European_Parts


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## nosborn94 (Feb 7, 2010)

Was the problem ever resolved?


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## 1pt8t (Mar 14, 2007)

Cody, did you ever figure this out? I read your other post with 17705 , 17544 , 16891. LOL it was in top 10 on google but no answer.

I have the same car, 2003 jetta 1.8t and I've done everything you've done, including the FULL 034 kit + billet valve and am having the same issues. No CEL before any of the repairs even tho breather hose was literally VTA - venting to atmosphere.

Anybody else have input here?


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