2007 Audi A4 cranks but doesn't start - ECM communication issues?

[houbaviy]

Hello,

I've been having intermittent starting issues with my Audi A4. The engine cranks but doesn't start. So far, I've been able to start it eventually and once it gets running everything is fine. The scan log lists the problems below, but scans at different times/mileages can vary. The "001672 - ECM Power Relay Load Circuit: (J271)" fault is there pretty much every time, but sometimes it is replaced by random cylinder misfire faults (at low RPM 0-500 RPM, i.e. during startup). The ABS fault seems to appear only if I've kept the ignition switch at "power on" for about 30 seconds before trying to crank and is accompanied by the corresponding warnings in the instrument cluster (ABS and stability control both). These disappear from the cluster upon restart. Sometimes I get an ECM - immobilizer communication fault in the log (sorry I don't have that log right now, so no code) and the "012423 - Voltage Supply Relay for Engine Components " is frequent but not there all the time. Finally, from time to time portions of the alphanumeric display in the instrument cluster are dimmer (i.e. sections of the OK symbol, low fuel, the CD/radio information etc. display). So there seems to be some lose connection somewhere (the J271 relay?), but why does the problem only happen on startup? Any pointers would be greatly appreciated. People have suggested fuel pump issues as the cause the "crank but doesn't start" problem, but given the codes below, we should probably rule problems with the fuel system out.

Regards,

Hristo

Saturday,11,October,2014,15:00:12:61059
VCDS -- Windows Based VAG/VAS Emulator
VCDS Version: 12.12.3.0
Data version: 20140905


VIN: WAUDF78E57A113517   License Plate: 
Mileage: 213030km-132370mi   Repair Order: 



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


Chassis Type: 8E (8E - Audi A4/S4/RS4 B6/B7 (2001 > 2008))
Scan: 01 02 03 08 09 0F 11 15 16 17 18 25 36 37 45 46 55 56 57 65
          67 69 75 76 77
 
VIN: WAUDF78E57A113517   Mileage: 213030km/132370miles
-------------------------------------------------------------------------------
Address 01: Engine        Labels: 06F-907-115-AXX.lbl
   Part No SW: 8E0 910 115 P    HW: 8E0 907 115 D
   Component: 2.0l R4/4V TFSI     0020  
   Revision: 5EH14---    Serial number:               
   Coding: 0104010A180F0120
   Shop #: WSC 08286 444 59089
   VCID: 2E531084B9F9C66E391-807B

2 Faults Found:
001672 - ECM Power Relay Load Circuit: (J271) 
               P0688 - 002 - Open Circuit - Intermittent
             Freeze Frame:
                    Fault Status: 00100010
                    Fault Priority: 0
                    Fault Frequency: 13
                    Reset counter: 255
                    Mileage: 208620 km
                    Time Indication: 0

             Freeze Frame:
                    RPM: 0 /min
                    Load: 0.0 %
                    Speed: 0.0 km/h
                    Temperature: 56.0∞C
                    Temperature: 51.0∞C
                    Absolute Pres.: 1010.0 mbar
                    Voltage: 0.000 V

012423 - Voltage Supply Relay for Engine Components 
               P3087 - 002 - Electrical Malfunction - Intermittent
             Freeze Frame:
                    Fault Status: 00100010
                    Fault Priority: 0
                    Fault Frequency: 2
                    Reset counter: 255
                    Mileage: 212809 km
                    Time Indication: 0

             Freeze Frame:
                    RPM: 238 /min
                    Load: 65.1 %
                    Speed: 0.0 km/h
                    Temperature: 57.0∞C
                    Temperature: 51.0∞C
                    Absolute Pres.: 1010.0 mbar
                    Voltage: 10.922 V

Readiness: 0000 0000

-------------------------------------------------------------------------------
Address 03: ABS Brakes        Labels: 8E0-910-517.clb
   Part No SW: 8E0 910 517 J    HW: 8E0 614 517 BH
   Component: ESP8 quattro    H06 0140  
   Revision: 00000000    Serial number: 00000000000000
   Coding: 0004526
   Shop #: WSC 06325 000 00000
   VCID: 2E531084B9F9C66E391-807B

1 Fault Found:
01314 - Engine Control Module 
            004 - No Signal/Communication - Intermittent
             Freeze Frame:
                    Fault Status: 00100100
                    Fault Priority: 1
                    Fault Frequency: 1
                    Reset counter: 38
                    Time Indication: 0

             Freeze Frame:
                    Hex Value: 0x0080
                    Hex Value: 0x0722
                    Hex Value: 0x0013
                    Hex Value: 0x8595
                    Hex Value: 0x0001

 

[DrPeter]

Hello,

Have a look at the Ross-Tech wiki pages for information about these fault codes.


17072/P0688/001672 - ECM Power Relay Load Circuit: (J271): Open Circuit


19543/P3087/012423 - Supply relay for engine components: Electrical error in circuit

You should also have a good wiring diagram for this vehicle and look at the J271 circuit to understand how this fault code could set.

Audi, Volkswagen and other Factory Repair Information website links can be found here:

Official Factory Repair Information

In short it could be a simple relay failure. It could also be a failed connection somewhere in the J271 circuit.

Hope this helps,

drpeter

 

[houbaviy]

Thanks and sorry for not going to the Wiki first. (I tried browsing for 001672, but that is hidden behind 17072. I put 001672 into the search field of the Wiki, but when it didn't autofill I gave up. Next time, I'll hit return.) I did look at the wiring diagrams in my Bentley, and as far as I understand the J271 relay load circuit includes the ignition coils and has nothing to do with the power to the actual ECM. Anyone familiar with relays - can the relay go bad in a way that would make it difficult to switch on initially but once switched on it would stay on? Regarding the faulty fuses and lose terminal mentioned in the Wiki wouldn't these cause random stalling of the engine as opposed to startup only problems? Sorry if these are stupid questions - I do Molecular Biology, electricity and magnetism was a l-o-o-o-n-g time ago.

Regards,

Hristo

 

[Uwe]

Anyone familiar with relays - can the relay go bad in a way that would make it difficult to switch on initially but once switched on it would stay on?

If it's really a mechanical relay with actual make/break contacts, it definitely can fail that way.

-Uwe-

 

[TrenSeta]

Has anyone been able to resolve this issue? I drive an 07 A4 and the symptoms directly reflect what is currently going on with car.

 

[Ashraf6119]

As advised by Mr Uwe you should check the Engine Control Relay or, it could be a dry joins in your ECU get someone to re-solder them by using the hot air gun.

 

[houbaviy]

Just for the sake of closure (and because someone asked me in a private message) - It WAS the ECM power relay.

 

[Grigor]

FYI, I have also had the same issue with a client's car and I decided to replace BOTH ECM relays (there are 2 ECM relays for a 2007 A4 cabrio quattro, maybe 2 for others as well - check your specific wiring diagram ). I'm 99% sure it'll fix the problem, I'll post here if it doesn't.
We did not do almost any troubleshooting (which sounds very wrong, I know) and here's why:
1. The codes clearly state ECM power supply issue
2. It started 1000 miles ago, happens intermittently (the worst ones to diagnose) and has happened 3 times over 1k miles.
3. The relays are 13+ years old with over 80k miles
4. We know that these relays fail kind-a often and there's an upgraded part#

So we just replaced them (both of them). To be specific:
J271-Motronic Engine Control Module (ECM) Power Supply Relay
J757-Engine Component Power Supply Relay