VW Golf IV (1J/2001) 1.4i Troubleshooting for fault code P0420 Catalyst system

   #1  

Juhis

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VCDS Serial number
HUC-2H
Hello,

This is my first post in this forum, so ask for some understanding.

Happened so far:
Engine caution light (MIL) came ON. Checked trouble codes, P0420 found. Reset the code, after that no faults. After running 1 or 2 days, light comes back with the same code. Catalysator, exhaust has been checked visually for leaks, no findings. Before having VCDS, sensor data read with Torque (free Android app) and Bluetooth adapter. O2 sensor B1S1 no graph (no errors or faults either). B1S2 reading fluctuating between 0,1-0,9V. Pre-catalysator O2 sensor (B1S1) replaced. B1S2 reading smoother, still no reading for B1S1. Engine running has been OK all the time. Measured exhaust pipe surface temperatures before and aft catalysator. Before ~240C, after >270C.Suppose that catalysator is working if not perfectly, but at least should be ok.

I would like to get good advice what to do next. I do not want buy catalysator to test if that would work of replace aft lambda (B1S2) before idea. Also thought if this could be wiring problem between sensor-ECU or ECU-OBD because of missing B1S1 reading. Having no wiring diagram cannot see if MIL is controlled directly by ECU or some other controller? Are there any VCDS tests, adaptation or coding to dig in further details? How to confirm that both lambdas are OK?

And tips or troubleshooting procedure would be appreciated.

Autoscan printout:

Code:
Friday,29,August,2014,16:50:09:32867
VCDS -- Windows Based VAG/VAS Emulator
VCDS Version: 12.12.2.0 (x64)
Data version: 20140212


VIN:    License Plate: TYM-431
Mileage: 296170km-184031mi   Repair Order: 



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


Chassis Type: 1J - VW Golf/Bora IV (1998 > 2006)
Scan: 01 02 03 08 15 16 17 19 22 29 35 36 37 39 46 47 55 56 57 75
          76
 
   Mileage: 296170km/184031miles
-------------------------------------------------------------------------------
Address 01: Engine        Labels: 036-906-032-AXP.lbl
   Part No: 036 998 032 P
   Component: ME7.5.10            5046  
   Coding: 00031
   Shop #: WSC 22000  
   VCID: 285400CAC873785EF37-5178

1 Fault Found:
16804 - Catalyst System; Bank 1 
            P0420 - 35-00 - Efficiency Below Threshold
Readiness: 0000 0000

-------------------------------------------------------------------------------
Address 03: ABS Brakes        Labels: 1C0-907-37x-ABS.lbl
   Part No: 1C0 907 379 C
   Component: ABS FRONT MK60      0103  
   Coding: 0001025
   Shop #: WSC 00046 615 1234567
   VCID: 2A50FAC2867F4A4EE53-5178

No fault code found.

-------------------------------------------------------------------------------
Address 15: Airbags        Labels: 6Q0-909-605-VW5.lbl
   Part No: 6Q0 909 605 A
   Component: 27 AIRBAG VW5  01   0006  
   Coding: 12855
   Shop #: WSC 00046  
   VCID: 356AD9BE0FC115B6781-4B32

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments        Labels: 1J0-920-xx5-17.lbl
   Part No: 1J0 920 805 
   Component: KOMBI+WEGFAHRS. BOO V04  
   Coding: 05111
   Shop #: WSC 00046  
   VCID: E3CED7E671D55B06665-515A

   Subsystem 1 - Part No: Ident
   Component: Nr. WEGFAHRS.:VWZ6Z0A3031525  
   Ident.-Nr. WEGFAHRS.:VWZ6Z0A3031525

No fault code found.

-------------------------------------------------------------------------------
Address 19: CAN Gateway        Labels: 6N0-909-901-19.lbl
   Part No: 6N0 909 901 
   Component: Gateway K<->CAN    0001  
   Coding: 00006
   Shop #: WSC 00046  
   VCID: F0E4A8AAB023F09EEB7-5178

No fault code found.

-------------------------------------------------------------------------------
Address 46: Central Conv.        Labels: 1J0-959-799.lbl
   Part No: 1J0 959 799 Q
   Component: 4C Zentral-SG Komf. 0001  
   Coding: 04097
   Shop #: WSC 00046  
   VCID: 4C9C9C5A7C4B747E37F-4B18

   Subsystem 1 - Part No: 1J1959801C
   Component: 4C Tõrsteuerger. FS0002r  

   Subsystem 2 - Part No: 1J1959802D
   Component: 4C Tõrsteuerger. BF0002r  

   Subsystem 3 - Part No: 1J4959811C
   Component: 4C Tõrsteuerger. HL0002r  

   Subsystem 4 - Part No: 1J4959812C
   Component: 4C Tõrsteuerger. HR0002r  

2 Faults Found:
00944 - Heated Exterior Mirror; Passenger Side (Z5) 
            35-00 - -
00935 - Electric Window Motor; Rear Right (V27) 
            62-10 - No or Incorrect Adjustment - Intermittent

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


Code:
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Address 46: DTCs cleared
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Address 01: DTCs cleared
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Address 01:036 998 032 P  channel 0 adapted from --- to 000
 
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