# Help please...code 16804 on VAG-COM...



## mr_e1974 (Jun 6, 2002)

Hi, I've got a recuring code that keeps throwing a CEL in my GTI. I've got a 2k1 GTI with the 12v VR6 and I keep getting the following code. 
16804 - Catalyst System; Bank 1: Efficiency Below Threshold
P0420 - 35 - 00 - - 

Has anyone else had this? I'm not sure if it's the Cat itself or one of the O2 sensors that may have gone bad. ANY help is appreciated. Thanks In Advance.


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## Theresias (Feb 11, 2004)

*Re: Help please...code 16804 on VAG-COM... (mr_e1974)*

http://wiki.ross-tech.com/inde...01056


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## mr_e1974 (Jun 6, 2002)

*Re: Help please...code 16804 on VAG-COM... (Theresias)*


_Quote, originally posted by *Theresias* »_http://wiki.ross-tech.com/inde...01056

Thanks for the link. http://****************.com/smile/emthup.gif







http://****************.com/smile/emthup.gif Is there any way to tell which O2 sensor to replace? On mine there is one pre-cat and one post-cat. That's a couple of hundred bucks in just sensors to replace... Can I check them with the VAG-COM???


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## dana vw tech (Sep 20, 2005)

*Re: Help please...code 16804 on VAG-COM... (mr_e1974)*

Please post your scan. There is a old recall (N7) related to that specific DTC on the MK4 99-02 AFP VR6 engines. It is a software update and with the scan data I can see if it was done or not.

_Quote, originally posted by *mr_e1974* »_ 
Thanks for the link. http://****************.com/smile/emthup.gif







http://****************.com/smile/emthup.gif Is there any way to tell which O2 sensor to replace? On mine there is one pre-cat and one post-cat. That's a couple of hundred bucks in just sensors to replace... Can I check them with the VAG-COM??? 

You can clear the fault and run the readiness tests. This will test all installed emissions systems including O2s & Cat. for example.
I haven't checked it out for a while (on the AFP) but there is most likely a guided plan within VCDS for your Ecm.


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## mr_e1974 (Jun 6, 2002)

*Re: Help please...code 16804 on VAG-COM... (dana vw tech)*


_Quote, originally posted by *dana vw tech* »_Please post your scan. There is a old recall (N7) related to that specific DTC on the MK4 99-02 AFP VR6 engines. It is a software update and with the scan data I can see if it was done or not.
You can clear the fault and run the readiness tests. This will test all installed emissions systems including O2s & Cat. for example.
I haven't checked it out for a while (on the AFP) but there is most likely a guided plan within VCDS for your Ecm.

I think that this is what you had asked for...I remember having to take my car in for some sort of TSB/computer reflash about 6 months ago. 
*System Scan*
Monday,29,June,2009,20:34:43:63821
VCDS Version: Release 805.4
Data version: 20090602
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

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

Mileage: 291200km/180943miles
-------------------------------------------------------------------------------
Address 01: Engine Labels: 021-906-018-AFP.lbl
Part No: 021 906 018 R
Component: MOTRONIC ME7.1 G 0004 
Coding: 00031
Shop #: WSC 00000 
1 Fault Found:
16804 - Catalyst System; Bank 1: Efficiency Below Threshold 
 P0420 - 35-00 - - 
Readiness: 0000 0000
-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 1C0-907-37x-ASR.lbl
Part No: 1C0 907 379 D
Component: ASR FRONT MK60 0103 
Coding: 0021505
Shop #: WSC 00000 785 00200
No fault code found.
-------------------------------------------------------------------------------
Address 08: Auto HVAC Labels: 3Bx-907-044.lbl
Part No: 3B1 907 044 C
Component: CLIMATRONIC C 1.0.0 
Coding: 01000
Shop #: WSC 00000 
1 Fault Found:
01274 - Air Flow Flap Positioning Motor (V71) 
37-00 - Faulty
-------------------------------------------------------------------------------
Address 15: Airbags Labels: 6Q0-909-605-VW5.lbl
Part No: 6Q0 909 605 F
Component: 08 AIRBAG VW6 0202 0004 
Coding: 12344
Shop #: WSC 00000 
1 Fault Found:
00532 - Supply Voltage B+ 
07-10 - Signal too Low - Intermittent
-------------------------------------------------------------------------------
Address 16: Steering wheel Labels: 1J0-907-487-A.lbl
Part No: 1J0 907 487 B
Component: Lenkradelektronik 0002 
Coding: 00008
Shop #: WSC 00000 
No fault code found.
-------------------------------------------------------------------------------
Address 17: Instruments Labels: 1J0-920-xx5-17.lbl
Part No: 1J0 920 925 D
Component: A4-KOMBIINSTR. VDO V01 
Coding: 07232
Shop #: WSC 00000 
Part No: IMMO
Component: IDENTNR: VWZ7Z0Y2735670 
IMMO-IDENTNR: VWZ7Z0Y2735670 
2 Faults Found:
00779 - Outside Air Temp Sensor (G17) 
30-10 - Open or Short to Plus - Intermittent
00779 - Outside Air Temp Sensor (G17) 
29-10 - Short to Ground - Intermittent
-------------------------------------------------------------------------------
Address 19: CAN Gateway Labels: 6N0-909-901-19.lbl
Part No: 6N0 909 901 
Component: Gateway K<->CAN 0001 
Coding: 00006
Shop #: WSC 00000 
No fault code found.
-------------------------------------------------------------------------------
Address 46: Central Conv. Labels: 1J0-959-799.lbl
Part No: 1J0 959 799 AJ
Component: 62 Zentral-SG Komf. 0001 
Coding: 00256
Shop #: WSC 00000 
Part No: 1J1959801C
Component: 62 Tõrsteuerger. FS0002r 
Part No: 1J1959802D
Component: 62 Tõrsteuerger. BF0002r 
1 Fault Found:
00944 - Heated Exterior Mirror; Passenger Side (Z5) 
35-00 - - 
End ---------------------------------------------------------------------
*Readiness Test*
Monday,29,June,2009,20:55:56:63821
VCDS Version: Release 805.4
Data version: 20090602
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

Readiness Status: 0110 1001
Exhaust Gas Recirculation: Passed
Oxygen Sensor Heating: Failed or Incomplete
Oxygen Sensor(s): Failed or Incomplete
Air Conditioning: Passed
Seconday Air Injection: Failed or Incomplete
Evaporative Emissions: Passed
Catalyst Heating: Passed
Catalytic Converter(s): Failed or Incomplete

Monday,29,June,2009,21:00:08:63821
VCDS Version: Release 805.4
Data version: 20090602
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

Readiness Status: 0110 1001
Exhaust Gas Recirculation: Passed
Oxygen Sensor Heating: Failed or Incomplete
Oxygen Sensor(s): Failed or Incomplete
Air Conditioning: Passed
Seconday Air Injection: Failed or Incomplete
Evaporative Emissions: Passed
Catalyst Heating: Passed
Catalytic Converter(s): Failed or Incomplete


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## mr_e1974 (Jun 6, 2002)

*Re: Help please...code 16804 on VAG-COM... (mr_e1974)*

I had let my car cool down for about 4 hours after driving home but it was still warm. Would that have caused the incomplete or failed results for the readiness tests?


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## dana vw tech (Sep 20, 2005)

*Re: Help please...code 16804 on VAG-COM... (mr_e1974)*

Your Software level is old. The recall doesn't look like it was done.
IM me the VIN.
The car probably was not driven long enough to run all of the tests.
I'll shoot you the individual tests (to run manually) tomorrow.


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## Uwe (Jan 16, 2000)

*Re: Help please...code 16804 on VAG-COM... (dana vw tech)*


_Quote, originally posted by *dana vw tech* »_The car probably was not driven long enough to run all of the tests.
I'll shoot you the individual tests (to run manually) tomorrow.

That shouldn't be necessary since VC has a "Guided Readiness" script for the AFP. Select -> 01-Engine -> Readiness -> Set Readiness. Follow the on-screen instructions.
-Uwe-


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## mr_e1974 (Jun 6, 2002)

*Re: Help please...code 16804 on VAG-COM... (Uwe)*


_Quote, originally posted by *Uwe* »_
That shouldn't be necessary since VC has a "Guided Readiness" script for the AFP. Select -> 01-Engine -> Readiness -> Set Readiness. Follow the on-screen instructions.
-Uwe-

I'll give that a try tomorrow or Thursday. Got home too late tonight and don't wanna pissoff the neighbors. I did notice that in step three it doesn't tell you to actually start the car. Thanks for the directions. I'll try them and post the results.


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## mr_e1974 (Jun 6, 2002)

*Re: Help please...code 16804 on VAG-COM... (Uwe)*


_Quote, originally posted by *Uwe* »_
That shouldn't be necessary since VC has a "Guided Readiness" script for the AFP. Select -> 01-Engine -> Readiness -> Set Readiness. Follow the on-screen instructions.
-Uwe-

Results from readiness test that I just finished...
Saturday,04,July,2009,13:09:23:63821
VCDS Version: Release 805.4
Data version: 20090602
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

Readiness Status: 0100 0001
Exhaust Gas Recirculation: Passed
Oxygen Sensor Heating: Failed or Incomplete
Oxygen Sensor(s): Passed
Air Conditioning: Passed
Seconday Air Injection: Passed
Evaporative Emissions: Passed
Catalyst Heating: Passed
Catalytic Converter(s): Failed or Incomplete

I noticed that with step 6 of the 13 for the readiness test that field 3 (Cat Conversion [MAX 0.55]) was reading 0.89 and so field 4 was Cat B1 NOT OK. 
Is the a way to change this parameter so that instead of the 0.55 max that I could set it at let's say 0.95? Right now I don't have any fault codes but when they pop up again I'll document them on here... Is there anyway to trick the computer to thinking that the cat is fine or am I S.O.L.?


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## dana vw tech (Sep 20, 2005)

*Re: Help please...code 16804 on VAG-COM... (mr_e1974)*


_Quote, originally posted by *mr_e1974* »_
Is the a way to change this parameter so that instead of the 0.55 max that I could set it at let's say 0.95? Right now I don't have any fault codes but when they pop up again I'll document them on here... Is there anyway to trick the computer to thinking that the cat is fine or am I S.O.L.? 

The updated software I mentioned previously does increase the tolerance. I do not know what it increases to right off. We don't see too many of those in the shop anymore.
Did you get anywhere with the other dealer? I would pursue that before you replace any components.
As far as VCDS goes, NO you are not going to alter the ecm / parameters.
It is only possible to update the Ecm with dealer scan tools because it ts a recall. We (technicians) do not get to pick or chose any parameters, It is a standardized data file that all the cars get. Any other means of tampering with or eliminating emission control devices are not done with dealer or VCDS equipment.


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## mr_e1974 (Jun 6, 2002)

*Re: Help please...code 16804 on VAG-COM... (dana vw tech)*


_Quote, originally posted by *dana vw tech* »_
The updated software I mentioned previously does increase the tolerance. I do not know what it increases to right off. We don't see too many of those in the shop anymore.
Did you get anywhere with the other dealer? I would pursue that before you replace any components.
As far as VCDS goes, NO you are not going to alter the ecm / parameters.
It is only possible to update the Ecm with dealer scan tools because it ts a recall. We (technicians) do not get to pick or chose any parameters, It is a standardized data file that all the cars get. Any other means of tampering with or eliminating emission control devices are not done with dealer or VCDS equipment.

I finally broke down and jacked up my car yesterday to "inspect" underneeth and well I can say that it looks like the shop I had took it into a few months ago to "fix" my exhaust REMOVED the cat and put in a straight pipe/test pipe with the O2 sensors in that. No wonder why I keep throwing codes.














I'm gonna have to look around here locally to find an exhaust shop to see what can be done. That's what I get for going to some little shop in my home town instead of a reputable shop. I get the feeling that this isn't going to be a "cheap fix".


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## BassNotes (Mar 16, 2005)

*Re: Help please...code 16804 on VAG-COM... (mr_e1974)*

Have you run readiness tests on the car?
I kept getting that code on my 1.8T every few months, and in addition, the car would pass readiness on all systems except the cat. Just to make sure, I ran the readiness script on VCDS also, and the cat failed each time, and the O2 sensors checked out. That made me certain that it was indeed a problem with the cat.
Since I was due for a smog check to renew my reg, I finally had the cat replaced last week with a low-mileage OE one I bought from a fellow vortexer. I ran the readiness script the next day, and everything passed. Then the next day I had the smog check, and the car passed with amazingly clean numbers.
It may be coincidental, but since the swap I also have no longer experienced the "hiccup" in first gear acceleration at around 3000 rpm that many owners complain about. I'd begun to think it was a "feature."


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## BassNotes (Mar 16, 2005)

Oh, never mind.


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