Whippet
Member
Hi - my 2001 A2 has been trouble free for the past 9 years. However after dismantling, cleaning, and reassembling the EGR sytem this weekend (including intake manifold, MAP sensor, EGR valve, EGR pipe, throttle body, and throttle body mounting plate), an ECU fault has emerged. Immediately after I completed the work (including throttle and EGR valve adaption), the car started without any hesitation, and the engine ran well. However, about 5 minutes into the post-work test drive, the dials (rpm and speed) momentarily dipped to zero, and the EPC, ABS, and brake warning lights came on and stayed on. The engine did not stall, but there was a dip in power. Pulled over; turned-off the ignition; restarted the car; and all of the warning lights disappeared, and the engine ran completely normally as if nothing was wrong. But the symptoms (dial dip + EPC, ABS, and brake warning lights) reappeared on each subsequent drive, sometimes within 5-10 minutes, sometimes after 30 minutes.
I ran this through VCDS, and it has logged an "intermittent communication" fault between the ECU to ABS module, and between the ECU to instrument cluster.
My first thought was that this is perhaps a loose wire - when I was working on the EGR system, I may have knocked the wiring loom during removal of the EGR pipe (it took a lot of persuasion to remove). I checked for any obvious signs of damage to/disruption of the wiring loom, but all look OK. For good measure, I also checked all of the earthing points. These were fine too.
My next thought was possible damage to the ECU during the EGR works. I was working with the engine cool, and the ignition off, but left the battery connected (bad practice) while disconnecting and reconnecting the various sensors and components (in this case: the MAP sensor, coil pack, throttle body).
The final thought is possible damage to the ECU due to MAP sensor. During the EGR works, I removed the original MAP sensor (Magnetti Marelli from 2001) and replaced it with a brand new Hella MAP sensor from Euro Car Parts. During the first VCDS scan after the post-work test drive, a fault was logged with the new MAP sensor (implausible signal, outside range). So I removed the Hella sensor, and replaced it with the original Magnetti Marelli unit (albeit, in a much cleaner state). Took it for another test drive, and re-scanned with VCDS. The MAP sensor measuring block returned to normal.
So, at the moment the car has an intermittent communication fault, but I'm not sure of the root of the problem. It definitely momentarily affects the ABS module and instrument cluster, and I think it's also momentarily affecting the ignition system/timing, as there is a slight dip in power when the fault occurs.
Has anyone experienced anything similar? Or any other ideas where to look? Thanks in advance for any feedback or pointers!
The current VCDS status is:
Monday,22,April,2019,20:17:58:32104
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 7 x86
VCDS Version: 18.9.1.0
Data version: 20190114 DS296.0
www.Ross-Tech.com
VIN: WAUZZZ8ZZ1N0392** License Plate: Y***YVA
Mileage: 119557 Repair Order: 20190422-1
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Chassis Type: 8Z (8Z - Audi A2 (2000 > 2005))
Scan: 01 02 03 08 15 16 17 18 37 45 46 56 57 75 76 77
VIN: WAUZZZ8ZZ1N0392**
-------------------------------------------------------------------------------
Address 01: Engine Labels: 036-906-034-APE.lbl
Part No: 036 906 034 Q
Component: MARELLI 4LV 3720
Coding: 00051
Shop #: WSC 00031
VCID: 20451FF6A0BE8B4AFD-4B00
WAUZZZ8ZZ1N0392** AUZ7Z0Y17328**
No fault code found.
Readiness: 0000 0001
-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 8Z0-907-379-MK20.lbl
Part No: 8Z0 907 379 B
Component: ESP 20 CAN V015
Coding: 10758
Shop #: WSC 02154
VCID: 4797A46A65D09C725C-4ACE
1 Fault Found:
01314 - Engine Control Module
49-10 - No Communications - Intermittent
-------------------------------------------------------------------------------
Address 17: Instruments Labels: 8Z0-920-xxx-17.lbl
Part No: 8Z0 920 950 A
Component: W1-KOMBIINSTR. VDO D13
Coding: 05442
Shop #: WSC 00164
VCID: 3C7DCB862C16CFAAC1-5102
WAUZZZ8ZZ1N0392** AUZ7Z0Y17328**
2 Faults Found:
01314 - Engine Control Module
49-10 - No Communications - Intermittent
01760 - Power Steering Control Module (J500) No comm. with Engine Control Module (ECM)
49-10 - No Communications - Intermittent
I ran this through VCDS, and it has logged an "intermittent communication" fault between the ECU to ABS module, and between the ECU to instrument cluster.
My first thought was that this is perhaps a loose wire - when I was working on the EGR system, I may have knocked the wiring loom during removal of the EGR pipe (it took a lot of persuasion to remove). I checked for any obvious signs of damage to/disruption of the wiring loom, but all look OK. For good measure, I also checked all of the earthing points. These were fine too.
My next thought was possible damage to the ECU during the EGR works. I was working with the engine cool, and the ignition off, but left the battery connected (bad practice) while disconnecting and reconnecting the various sensors and components (in this case: the MAP sensor, coil pack, throttle body).
The final thought is possible damage to the ECU due to MAP sensor. During the EGR works, I removed the original MAP sensor (Magnetti Marelli from 2001) and replaced it with a brand new Hella MAP sensor from Euro Car Parts. During the first VCDS scan after the post-work test drive, a fault was logged with the new MAP sensor (implausible signal, outside range). So I removed the Hella sensor, and replaced it with the original Magnetti Marelli unit (albeit, in a much cleaner state). Took it for another test drive, and re-scanned with VCDS. The MAP sensor measuring block returned to normal.
So, at the moment the car has an intermittent communication fault, but I'm not sure of the root of the problem. It definitely momentarily affects the ABS module and instrument cluster, and I think it's also momentarily affecting the ignition system/timing, as there is a slight dip in power when the fault occurs.
Has anyone experienced anything similar? Or any other ideas where to look? Thanks in advance for any feedback or pointers!
The current VCDS status is:
Monday,22,April,2019,20:17:58:32104
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 7 x86
VCDS Version: 18.9.1.0
Data version: 20190114 DS296.0
www.Ross-Tech.com
VIN: WAUZZZ8ZZ1N0392** License Plate: Y***YVA
Mileage: 119557 Repair Order: 20190422-1
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Chassis Type: 8Z (8Z - Audi A2 (2000 > 2005))
Scan: 01 02 03 08 15 16 17 18 37 45 46 56 57 75 76 77
VIN: WAUZZZ8ZZ1N0392**
-------------------------------------------------------------------------------
Address 01: Engine Labels: 036-906-034-APE.lbl
Part No: 036 906 034 Q
Component: MARELLI 4LV 3720
Coding: 00051
Shop #: WSC 00031
VCID: 20451FF6A0BE8B4AFD-4B00
WAUZZZ8ZZ1N0392** AUZ7Z0Y17328**
No fault code found.
Readiness: 0000 0001
-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 8Z0-907-379-MK20.lbl
Part No: 8Z0 907 379 B
Component: ESP 20 CAN V015
Coding: 10758
Shop #: WSC 02154
VCID: 4797A46A65D09C725C-4ACE
1 Fault Found:
01314 - Engine Control Module
49-10 - No Communications - Intermittent
-------------------------------------------------------------------------------
Address 17: Instruments Labels: 8Z0-920-xxx-17.lbl
Part No: 8Z0 920 950 A
Component: W1-KOMBIINSTR. VDO D13
Coding: 05442
Shop #: WSC 00164
VCID: 3C7DCB862C16CFAAC1-5102
WAUZZZ8ZZ1N0392** AUZ7Z0Y17328**
2 Faults Found:
01314 - Engine Control Module
49-10 - No Communications - Intermittent
01760 - Power Steering Control Module (J500) No comm. with Engine Control Module (ECM)
49-10 - No Communications - Intermittent
Last edited:
