98 Jetta AHU TDI: Engine Light & Limp Mode with electrical faults, N108, G70, EGR

   #1  

CarnieTDI

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New user, looking to get verified. Have VCDS and codes to share for troubleshooting help.

1998 VW Jetta, AHU TDI, 154K, engine light comes on about 10 seconds after start and car runs in limp mode.
VIN: 3VWTL8AJ4AM644784
Symptoms were a slow and intermittent onset, but are now always there.

I did a physical inspection and replaced a couple old hoses off of the MAF sensor.
I replaces a bad hose in the brain box years ago.
Any help with probable causes of the codes below would be greatly appreciated.
The car won't pass California SMOG in current condition.

Thanks for looking!
-Carnie

Code:
Monday,04,November,2019,17:54:21:16662
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 19.6.2.0 (x64)
Data version: 20190930 DS308.0
[url]www.Ross-Tech.com[/url]




Chassis Type: 1H - VW Golf/Vento III (1992 > 1999)
Scan: 01 02 03 08 12 15 25 41 56
 
-------------------------------------------------------------------------------
Address 01: Engine        Labels: 028-906-021-AHU.lbl
   Part No: 028 906 021 JB
   Component: 1,9l R4 EDC  G40SG  1457  
   Coding: 00002
   Shop #: WSC 00066  
   VCID: 58BF7A62B8527D8FBF-4AE8

3 Faults Found:
01269 - Commencement of Injection Valve (N108) 
            31-10 - Open or Short to Ground - Intermittent
00553 - Mass Air Flow Sensor (G70) 
            27-10 - Implausible Signal - Intermittent
00560 - Exhaust Gas Recirculation System 
            17-10 - Control Difference - Intermittent
Readiness: N/A

-------------------------------------------------------------------------------
Address 15: Airbags        Labels: 1J0-909-60x-VW3.lbl
   Part No: 1J0 909 603 T
   Component: AIRBAG VW3 -        V03  
   Coding: 00084
   Shop #: WSC 00066  
   VCID: 3A7BC0EA261E8F9FA9-4B00

2 Faults Found:
00588 - Airbag Igniter; Driver Side (N95) 
            32-10 - Resistance Too High - Intermittent
00532 - Supply Voltage B+ 
            07-10 - Signal too Low - Intermittent

End-------------------------(Elapsed Time: 02:17)--------------------------
 
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   #2  

Uwe

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If it were mine, I'd start by check wiring diagrams to see if N108, G70 and the EGR system have anything in common, like a source of power or a ground.

-Uwe-
 
   #3  

CarnieTDI

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Uwe, good call. Looking through the manual, all 3 items are on the T68-68 pin connector. I'll look into cleaning that.
N108 Cold Start Valve is on Ground 56
G70 MAF Sensor is on Ground 56.
N18 EGR Vacuum Regulator Solenoid Valve is on Ground 52.

I'll get to work on those tomorrow. Thanks for the steerage.
-Carnie
 
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CarnieTDI

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I don't suppose anyone has a ground map that shows the physical locations of Ground 52 and Ground 56?
I cleaned the ones under the battery tray.
 
   #5  

CarnieTDI

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Success.
I'm not sure exactly which one fixed it but after doing the following and clearing the codes, the check engine light is gone:
1. Removed battery, battery tray, cleaned both ground lugs under the battery tray.
2. Cleaned the ground lug on the passenger side of the engine under the 24 pin connector and coolant hoses. (Has 3 small wires)
3. Removed the T-68, 68 pin connector from the ECU (all engine sensors are connected to this) cleaned pins with electrical contact cleaner, applied a contact enhancer, and lubricated seals with dielectric grease.
4. Started engine. Check engine light was still present.
5. Cleared codes.
6. Started engine, drove a few miles. Still no check engine light.

Ok, now off to get it smogged, quick before it comes back.

-Carnie
 
   #6  

Uwe

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