# Mk5 2.0 t fsi P0688 troubles :( - please help



## Lukethor (Jan 14, 2013)

Hi all 
Ive been having some trouble with my 05 plate mk5 Gti

it all started on saturday, i drove home to pick my misses up, when i went to re-start the car it just cranked over.
checked codes on VCDS - not codes.

after a few mins looking i found a 20 amp fuse blown in the under bonnet fuse/relay box next to the battery.

i fitted a new fuse and turned the engine over and she fired up but on 3 cylinders, shortle followed by some smoke from number 4 coil pack. 

the coil pack shorted to positive and had a small melt down and melted the plug slightly on no4.

confident i just needed to replace the coil pack and plug i ordered a set of coils, plugs and dug a spare plug out of the garage and replaced the melted item.

once fitted i cranked the engine - but she wouldnt fire.

i plugged in VCDS again and to my annoyance the code; 
001672 ECM power relay load circuit (J271)- P0688 -004 - open circuit had shown up when the key is turned to ignition on.
i headded out to GSF with the 3 under bonnet relays in hand and managed to get hold of the furthest from the battery and the black one in the middle of the box (i dont know what ones they are) but the 5 pin one closest tot he battery was unavailable.

i cranked the engine again but no joy. - still the same code.

i bridged the two big terminals on the far relay from the battery (already replaced) and the trouble code then went when ignition was on. thinking i'd cracked it i cranked again and the following TC's came up

008521 supply voltage for fuel injector group B p2149 - 002 - OPEN CIRCUIT

012423 - voltage supply relay for engine components p3087 - 004 -electrical malfunction

008521 - supply voltage for fuel injector group B p02149 - 002- open circuit

008518 - supply voltage for fuel injector group A p2146 - 002 - 0pen circuit


Ive googled the fault etc but i cane seem to find anyone who has managed to repair this fault?

Can anyone help me please!!!


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## Lukethor (Jan 14, 2013)

Right - i have some progress today, i have no idea which relay is officially ECM j271 but hopefully if i write this all up start to finish it will be of help to others in future!!!

The VCDS print out:

Chassis Type: 1K0
Scan: 01 02 03 08 09 15 16 17 19 25 42 44 46 52 55 56 62 72 76

VIN: WVWZZZ1KZ6W006626 Mileage: 101280km/62932miles


Address 01: Engine Labels: 06F-907-115-AXX.lbl
Part No SW: 1K0 907 115 A HW: 1K0 907 115 A
Component: 2.0l R4/4V TFSI G00 0070 
Revision: --H01--- Serial number: VWZ7Z0E2157244
Coding: 040300031C070160
Shop #: WSC 00581 210 83422
VCID: 244DC102E7B8EB3865D

3 Faults Found:
001672 - ECM Power Relay Load Circuit: (J271) 
P0688 - 004 - Open Circuit
Freeze Frame:
Fault Status: 01100100
Fault Priority: 0
Fault Frequency: 1
Mileage: 101287 km
Time Indication: 0
Date: 2000.00.00
Time: 19:33:51

Freeze Frame:
RPM: 0 /min
Load: 0.0 %
Speed: 0.0 km/h
Temperature: 3.0°C
Temperature: 5.0°C
Absolute Pres.: 990.0 mbar
Voltage: 0.000 V

008518 - Supply Voltage for Fuel Injector Group A 
P2146 - 002 - Open Circuit
Freeze Frame:
Fault Status: 01100010
Fault Priority: 0
Fault Frequency: 1
Mileage: 101287 km
Time Indication: 0
Date: 2000.00.00
Time: 19:37:31

Freeze Frame:
RPM: 203 /min
Load: 88.6 %
Speed: 0.0 km/h
Temperature: 3.0°C
Temperature: 5.0°C
Absolute Pres.: 990.0 mbar
Voltage: 7.620 V

008521 - Supply Voltage for Fuel Injector Group B 
P2149 - 002 - Open Circuit
Freeze Frame:
Fault Status: 01100010
Fault Priority: 0
Fault Frequency: 1
Mileage: 101287 km
Time Indication: 0
Date: 2000.00.00
Time: 19:37:31

Freeze Frame:
RPM: 220 /min
Load: 87.4 %
Speed: 0.0 km/h
Temperature: 3.0°C
Temperature: 5.0°C
Absolute Pres.: 990.0 mbar
Voltage: 10.541 V

Readiness: 0110 0101


I only get 001672 (P0688) before cranking the engine at which point i also get the injector DTC's in the system also. (SEE READOUT BELOW)

I replaced relays 1,2 & 4 in the under bonnet fuse box hoping one was the ECM (J271 relay) but this changed nothing.
If i bridge relay terminals 30 & 87 of R4 as labeled in the box (or A4 by the diagram below) then i dont get DTC P0688 however its replaced with a new code (bridged relay print out below) 










Address 01: Engine Labels: 06F-907-115-AXX.lbl
Control Module Part Number: 1K0 907 115 A HW: 1K0 907 115 A
Component and/or Version: 2.0l R4/4V TFSI G00 0070
Software Coding: 040300031C070160
Work Shop Code: WSC 00581 210 83422
VCID: 244DC102E7B8EB3865D
5 Faults Found:

012423 - Voltage Supply Relay for Engine Components 
P3087 - 004 - Electrical Malfunction
Freeze Frame:
Fault Status: 01100100
Fault Priority: 0
Fault Frequency: 1
Mileage: 101287 km
Time Indication: 0
Date: 2000.00.00
Time: 04:14:07

Freeze Frame:
RPM: 221 /min
Load: 84.7 %
Speed: 0.0 km/h
Temperature: 5.0°C
Temperature: 7.0°C
Absolute Pres.: 990.0 mbar
Voltage: 10.287 V

008521 - Supply Voltage for Fuel Injector Group B 
P2149 - 002 - Open Circuit
Freeze Frame:
Fault Status: 01100010
Fault Priority: 0
Fault Frequency: 1
Mileage: 101287 km
Time Indication: 0
Date: 2000.00.00
Time: 04:14:07

Freeze Frame:
RPM: 276 /min
Load: 76.4 %
Speed: 0.0 km/h
Temperature: 5.0°C
Temperature: 7.0°C
Absolute Pres.: 990.0 mbar
Voltage: 2.032 V

008518 - Supply Voltage for Fuel Injector Group A 
P2146 - 002 - Open Circuit
Freeze Frame:
Fault Status: 01100010
Fault Priority: 0
Fault Frequency: 1
Mileage: 101287 km
Time Indication: 0
Date: 2000.00.00
Time: 04:14:07

Freeze Frame:
RPM: 276 /min
Load: 76.4 %
Speed: 0.0 km/h
Temperature: 5.0°C
Temperature: 7.0°C
Absolute Pres.: 990.0 mbar
Voltage: 11.557 V

008521 - Supply Voltage for Fuel Injector Group B 
P2149 - 002 - Open Circuit
Freeze Frame:
 Fault Status: 01100010
Fault Priority: 0
Fault Frequency: 1
Mileage: 101287 km
Time Indication: 0
Date: 2000.00.00
Time: 04:14:07

Freeze Frame:
RPM: 592 /min
Load: 68.6 %
Speed: 0.0 km/h
Temperature: 5.0°C
Temperature: 6.0°C
Absolute Pres.: 990.0 mbar
Voltage: 10.922 V

008518 - Supply Voltage for Fuel Injector Group A 
P2146 - 002 - Open Circuit
Freeze Frame:
Fault Status: 01100010
Fault Priority: 0
Fault Frequency: 1
Mileage: 101287 km
Time Indication: 0
Date: 2000.00.00
Time: 04:14:07

Freeze Frame:
RPM: 592 /min
Load: 66.6 %
Speed: 0.0 km/h
Temperature: 5.0°C
Temperature: 6.0°C
Absolute Pres.: 990.0 mbar
Voltage: 12.192 V


Readiness: 0110 0101

Just to cover all bases, fuses 6,9,10,11,12 only recieve 0.54 volts untill i bridge the relay at which point they recieve battery voltage.
on the relay i have battery voltage at pin 30 and continuity from pin 87 to the relivant fuses.
Pin 86 has battery voltage which so far is all correct.
however pin 85 has 3.45 volts which i think is wrong? - (WIRING DIAG BELOW)










in the morning im going to pull out the ecu and check continuity from pin 69 on the ecu plug to pin 85 on the relay but from that point im a little stuck.
im kind of hoping someone will turn around and tell me im an idiot and i need to replace some random relay or tell me how they have resolved this issue before?? im also asuming at this point that the injector codes are linked to the relay fault as they seem to take power direct from the ECU?

as ever any help is appreciated, i have this on 4 forums at the moment and not one bit of help so far 

thanks all


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## Lukethor (Jan 14, 2013)

Right, the ECU has been off for a bench test at BBA Remen - and has come back with no fault found - any ideas anyone??


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## Tagme (Jun 11, 2007)

Seems like I'mhaving the same problem with my A3 2.0T 2006 (wich is a GTI)... I'm haveng the same code P0688 plus U0100... I'm trying to check the fuses with a test light but half of 'em don't work... So My problem is not the fuses themselves... I guess I have some kind of ground problem... Did you figure out what was your problem?


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## revolic (Apr 4, 2014)

Solved problem )
BAD E-BOX


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## SkodaCov (12 mo ago)

revolic said:


> Solved problem )
> BAD E-BOX


sorry to revive a really old post but by EBox do u mean the EVAP box?


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