Hello there, Jimble here,

My Audi A6 C7 2014 (15 plate) is having a no crank no start issue and I would like any input as I have got confused and I'm struggling. I'll give as detailed a history of faults and a breakdown of what I know and have done so far to the car. I can provide auto scans of previous states through this journey I'm on here.

I bought the car in February 2022 with everything in working order. About 6 months into ownership I got the dash light "Headlight range control fault". I never investigated or cleared this.

Skip forward to late 2024 early 2025 - I'm getting intermittent dash lights to accompany the HL range dash light (TPMS, ESC, START/STOP) and losing auto hold brake and cruise control. This problem seemed more likely to present itself in wet weather but not 100% of the time. Sometimes, stopping the car and turning it off would allow it to go away such as in short trips.

I've also had on rare occasion the speedo needle act erratically and what feels like engine power pulses as if dropping out for a split second.

October 2025 - No start/crank

Inspecting the engine bay I discovered a classic blocked drain hole (composted leaves) by the ECM and relay box. Relay box corner screw faceless from rust, ECM heavily oxidised. No clear sign of any water ingress into the relay box. The ECM does concern me with a small area on the underside plating where the aluminium casting has oxidised very close to the seal and may have breached. When connected on bench it communicates and reports it's in connection hell so I assume it's working. In the car however, it can only be reached when the engine is running (bridged relay).

Oscilloscope on the cars CAN H + L at the OBD2 port gives me signals that I'm unable to understand or shape into the square wave I see it should be. (Bought the scope, never used it until now so I'm learning). I may scope the ECM on the bench to test before opening it up should anyone believe it worth doing before trying anything else first.

Bridging relay 645 in the plenum chamber allows starting and the car drives like it always has. It also produces less faults if bridged and engine running.

I replaced the ride height sensor on the left side due to reporting a short. The sensor was seized solid, fitted new one, still reports short.

Car is currently sitting with the headlight range control module disconnected. I was thinking this may have caused CAN interference and I may need to replace it as well so no point putting the dash back yet.

I'm available to try your suggestions all day so I will be keeping an eye here for any advice. I will also most likely be popping down to get a new battery today, the original is still in there stamped: 45-14 😏 So I'd like to rule that out at least.

Edited April 23Apr 23 by JiMbLeFiSh

How would I go about uploading a VCDS scan?

Edited April 23Apr 23 by JiMbLeFiSh
Scan too long and poorly formatted

Welcome Jamie,

Straight from the book of Simple First Priniciples, if this 11 year old car is running on its original battery, then it’s daft to be delving in depth into any parameters until the battery has been renewed and coded to the car.

Obviously your choice, but I’m favouring Exide, following a couple of dissatisfactions with Varta/Bosch.

Regards,

Gareth.

p.s. You’ve filled half my computer memory in two posts!

Think twice. No one is likely to read through all of that.

Do you have any comments on replacing the battery?

Regards,

Gareth.

Apologies for not getting back to you all and thank you for responding. I've been burning the candle both ends a little. I am here now though.

Just picked up and installed Platinum AGM 95ah battery but module 61 either doesn't exist or can't be reached. It has never shown in an auto scan to date... otherwise I'd code it in.

Did a scan after battery fit and then cleared DTC's. I was mid second scan when laptop died so I'm just waiting for a charge and then I'll complete a second scan.

New battery installed, 3ah more than last at 95ah. Battery coded using 19 - CAN gateway (UDS) as module 61 does not appear in the installed module list.

Second scan in progress. Currently with ignition on and not running I am receiving no +12v at pin 3 on ECM 🤷🏻‍♂️

Edited April 24Apr 24 by JiMbLeFiSh

20 minutes ago, JiMbLeFiSh said:

New battery installed, 3ah more than last at 95ah. Battery coded using 19 - CAN gateway (UDS) as module 61 does not appear in the installed module list.

Second scan in progress. Currently with ignition on and not running I am receiving no +12v at pin 3 on ECM 🤷🏻‍♂️

20 minutes ago, JiMbLeFiSh said:

New battery installed, 3ah more than last at 95ah. Battery coded using 19 - CAN gateway (UDS) as module 61 does not appear in the installed module list.

Second scan in progress. Currently with ignition on and not running I am receiving no +12v at pin 3 on ECM 🤷🏻‍♂️

I'm getting +12v at ECM when relay 645 bridged in plenum relay box. Any ideas where to look next? Tools and time at the ready.

With relay 645 bridged, ignition and engine on, second scan and a clear of DTC's shows all dash lights out and only 12 faults. Driver dash and Headlight range control still disconnected.

Could any of these faults be down to a necessary calibration?

01-Engine -- Status: OK 0000

03-ABS Brakes -- Status: Malfunction 0010

04-Steering Angle -- Status: OK 0000

05-Acc/Start Auth. -- Status: Malfunction 0010

08-Auto HVAC -- Status: OK 0000

09-Cent. Elect. -- Status: Malfunction 0010

10-Park/Steer Assist -- Status: OK 0000

15-Airbags -- Status: Malfunction 0010

16-Steering wheel -- Status: OK 0000

17-Instruments -- Status: Malfunction 0010

19-CAN Gateway -- Status: Malfunction 0010

3B-Sensor Elect. -- Status: OK 0000

42-Door Elect, Driver -- Status: OK 0000

44-Steering Assist -- Status: OK 0000

46-Central Conv. -- Status: Malfunction 0010

52-Door Elect, Pass. -- Status: OK 0000

53-Parking Brake -- Status: Malfunction 0010

55-Headlight Range -- Status: Cannot be reached 0100

5F-Information Electr. -- Status: OK 0000

62-Door, Rear Left -- Status: OK 0000

72-Door, Rear Right -- Status: OK 0000

AC-Reductant Control -- Status: OK 0000

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

Address 03: ABS Brakes (J104) Labels:. 4G0-907-379-V1.clb

Part No SW: 4G0 907 379 L HW: 4G0 907 379 L

Component: ESP PREMIUM H09 0450

Revision: -------- Serial number: --------------

Coding: 06A09F016005F9809B00

Shop #: WSC 02391 785 00200

ASAM Dataset: EV_ESPPremiAU57X 004039

ROD: EV_ESPPremiAU57X_004_AU57.rod

VCID: 3A7B87EFBD5F904BCE-806E

2 Faults Found:

0781 - Function Restricted due to Missing Message(s)

U1111 00 [00001001] - -

[New feature! Extended UDS fault detail is only supported by current gen. interfaces]

Confirmed - Tested Since Memory Clear

Freeze Frame:

Fault Priority: 6

Fault Frequency: 1

Reset counter: 90

Mileage: 153160 km

Date: 2026.04.19

Time: 01:54:33

VzRef: 00

Bit Info 1: 00

Bit Info 2: 40

Bit Info 3: 00

Bit Info 4: 1F

F-Path: 00

F-Type: E2

Uz: B9

0687 - Function Restriction due to Faults in Other Modules

U1113 00 [00001001] - -

[New feature! Extended UDS fault detail is only supported by current gen. interfaces]

Confirmed - Tested Since Memory Clear

Freeze Frame:

Fault Priority: 6

Fault Frequency: 1

Reset counter: 90

Mileage: 153160 km

Date: 2026.04.19

Time: 01:54:33

VzRef: 00

Bit Info 1: 00

Bit Info 2: 40

Bit Info 3: 02

Bit Info 4: 1F

F-Path: 00

F-Type: B5

Uz: B9

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

Address 05: Acc/Start Auth. (J393) Labels:. 8K0-907-064-05.clb

Part No SW: 4H0 907 064 FN HW: 4H0 907 064 EN

Component: BCM2 2.0 H36 0560

Revision: 00002001

Coding: 03B83046000000000000

Shop #: WSC 02391 785 00200

VCID: 7AFB47EFF5DF504B8E-802E

Subsystem 2 - Part No SW: 4H0 905 852 C HW: 4H0 905 852 C

Component: J764 ELV MLB H40 0046

Serial number: 3214000126482014

1 Fault Found:

01330 - Central Control Module for Central Convenience (J393)

013 - Check DTC Memory

Freeze Frame:

Fault Status: 01101101

Fault Priority: 6

Fault Frequency: 1

Reset counter: 90

Mileage: 153160 km

Time Indication: 0

Date: 2026.04.19

Time: 01:54:32

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

Address 09: Cent. Elect. (J519) Labels:. 4H0-907-063-V1.clb

Part No SW: 4H0 907 063 CF HW: 4H0 907 063 F

Component: BCM1 2.0 H12 0130

Revision: 20012002 Serial number: 00000001943917

Coding: 2600201040349F600481008300001D0C0F9D830827090201000004606100

Shop #: WSC 02391 785 00200

VCID: 6ED37BBFB9970CEB22-803A

Subsystem 1 - Part No SW: 4G2 955 119 HW: 4G8 955 119 A Labels: 1KX-955-119.CLB

Component: WWS57X 140919 H37 0080

Serial number: 141008214735

Coding: 0045F7

Subsystem 2 - Part No SW: 8U0 955 559 B HW: 8U0 955 559 B Labels: 8U0-955-559.CLB

Component: G397_RLFS H06 0002

Serial number: 23396378

Coding: 02006D

Subsystem 3 - Part No SW: 4G0 907 658 A HW: 4G0 907 658 A

Component: Humidity_Sens H03 0002

Serial number: 2E280557000000000001

3 Faults Found:

01771 - Control Module for Headlight Range (J431)

004 - No Signal/Communication

Freeze Frame:

Fault Status: 01100100

Fault Priority: 6

Fault Frequency: 1

Reset counter: 90

Mileage: 153160 km

Time Indication: 0

Date: 2026.04.19

Time: 01:54:00

01800 - Light Switch (E1)

004 - No Signal/Communication

Freeze Frame:

Fault Status: 01100100

Fault Priority: 3

Fault Frequency: 1

Reset counter: 90

Mileage: 153160 km

Time Indication: 0

Date: 2026.04.19

Time: 01:54:00

03280 - Switch Position of Light-Switch Knob

008 - Implausible Signal

Freeze Frame:

Fault Status: 01101000

Fault Priority: 3

Fault Frequency: 1

Reset counter: 90

Mileage: 153160 km

Time Indication: 0

Date: 2026.04.19

Time: 01:54:00

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

Address 15: Airbags (J234) Labels:* 4H0-959-655.clb

Part No SW: 4H0 959 655 C HW: 4H0 959 655 C

Component: Airbag10.43 H43 0040

Revision: -------- Serial number: 003JG00KH2WN Dataset Number: 4G0909602H 0002

Coding: 3032343631324E303235554A305234473053

Shop #: WSC 02391 785 00200

ASAM Dataset: EV_AirbaAU10BPAAU64X 001014

ROD: EV_AirbaAU10BPAAU64X_VW51.rod

VCID: 366393DF8947742B2A-8062

Crash sensor for side airbag: driver side:

Serial number: 3575HRB40592PMPQ88IC

Crash sensor for side airbag: passenger side:

Serial number: 3585HRB404V2PMPQBONF

Rear Side Airbag Crash Sensor (on driver's side):

Serial number: 3515JRB405H31R1QMH3P

Passenger side rear thorax airbag crash sensor:

Serial number: 3525JRB406332020L13V

Crash sensor for front airbag: driver side:

Serial number: 3554VRB405H32IIGG9AW

Crash sensor for front airbag: passenger side:

Serial number: 3564VRB405332IIGM14B

1 Fault Found:

1048581 - Databus

U1123 00 [00001001] - Received Error Message

[New feature! Extended UDS fault detail is only supported by current gen. interfaces]

Confirmed - Tested Since Memory Clear

Freeze Frame:

Fault Priority: 6

Fault Frequency: 1

Reset counter: 90

Mileage: 153160 km

Date: 2026.04.19

Time: 01:54:33

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

Address 17: Instruments (J285) Labels:| 4H0-920-xxx-17.clb-SRI1

Part No SW: 4G8 920 984 H HW: 4G8 920 984 H

Component: TDieGb H58 0622

Revision: 29460237 Serial number: 658190914596017

Coding: 33A40A000B412600010000

Shop #: WSC 02391 785 00200

ASAM Dataset: EV_RBD4K 004048

ROD: EV_RBD4K_AU57.rod

VCID: 3B7582EBB265A943D5-806E

1 Fault Found:

16776970 - Function Restricted due to Missing Message(s)

U1111 00 [00001001] - -

[New feature! Extended UDS fault detail is only supported by current gen. interfaces]

Confirmed - Tested Since Memory Clear

Freeze Frame:

Fault Priority: 6

Fault Frequency: 1

Reset counter: 90

Mileage: 153160 km

Date: 2026.04.19

Time: 01:54:32

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

Address 19: CAN Gateway (J533) Labels:| 4H0-907-468.clb

Part No SW: 4G0 907 468 AD HW: 4G0 907 468 AC

Component: J533--Gateway H13 0050

Revision: -------- Serial number: 00000001609691 Dataset Number: 4G0909515H 0067

Coding: 00CD074400

Shop #: WSC 02391 785 00200

GVL: BDA1C800DC6060030000

ASAM Dataset: EV_GatewPkoUDS 001019

ROD: EV_GatewPkoUDS_001_AU57.rod

VCID: 72EB6FCFA5AF280BC6-8026

Battery Monitoring Control Module:

Subsystem 1 - Part No SW: 8T0 915 181 HW: 8T0 915 181

Component: J367-BDMHella H03 8041

Serial number: 1140874703

Voltage stabilizer:

Subsystem 2 - Part No SW: 8K0 959 663 D HW: 8K0 959 663

Component: J532_DCDCStab H23 0021

Serial number: 140828000000000002FC

2 Faults Found:

5013 - Headlight Range Control Module

U101E 00 [00001001] - No Communication

Confirmed - Tested Since Memory Clear

Freeze Frame:

Fault Priority: 2

Fault Frequency: 1

Reset counter: 90

Mileage: 153160 km

Date: 2026.04.19

Time: 01:54:33

Voltage terminal 30: 14.2 V

Voltage terminal 15: 14.4 V

Control Module temperature: 27 °C

System status: Terminal 15 on

IN ESP_standstill flag: standstill detected

Engine running: On

IN ZAS_Te_X: On

Terminal 15 status via CAN: On

Terminal 15 status: On

Datenfeld: 0

0259 - Extended CAN Bus (SAE Bus C)

U0047 00 [00001001] - Performance

[New feature! Extended UDS fault detail is only supported by current gen. interfaces]

Confirmed - Tested Since Memory Clear

Freeze Frame:

Fault Priority: 2

Fault Frequency: 1

Reset counter: 90

Mileage: 153160 km

Date: 2026.04.19

Time: 01:54:33

Voltage terminal 30: 14.2 V

Voltage terminal 15: 14.4 V

Control Module temperature: 27 °C

System status: Terminal 15 on

IN ESP_standstill flag: standstill detected

Engine running: On

IN ZAS_Te_X: On

Terminal 15 status via CAN: On

Terminal 15 status: On

Datenfeld: 0

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

Address 46: Central Conv. (J393) Labels:. 4H0-907-064-46.clb

Part No SW: 4H0 907 064 FN HW: 4H0 907 064 EN

Component: BCM2 2.0 H36 0560

Revision: 00002001 Serial number: 0351166896

Coding: 011B062280B900408320080400010E470000000000000000000000000000

Shop #: WSC 02391 785 00200

VCID: 7AFB47EFF5DF504B8E-802E

Subsystem 1 - Part No: 4G0 951 177

Component: DWA-Sensor H01 0010

Subsystem 2 - Part No: 1K0 951 605 C

Component: LIN BACKUP HO H05 1501

1 Fault Found:

00457 - Central Electronics Control Module / BCM (J519)

013 - Check DTC Memory

Freeze Frame:

Fault Status: 01101101

Fault Priority: 6

Fault Frequency: 1

Reset counter: 90

Mileage: 153160 km

Time Indication: 0

Date: 2026.04.19

Time: 01:54:32

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

Address 53: Parking Brake (----) Labels: 4H0-907-801.clb

Part No SW: 4H0 907 801 H HW: 4H0 907 801 A

Component: EPB-4 H04 0015

Revision: -------- Serial number: 00000001253499 Dataset Number: 4G0909522D 0007

ASAM Dataset: EV_ParkiBrake 001028

ROD: EV_ParkiBrake_VW51.rod

VCID: 2D51BCB37C1137F35B-8078

1 Fault Found:

465152 - Function Restriction due to Faults in Other Modules

U1113 00 [00001001] - -

[New feature! Extended UDS fault detail is only supported by current gen. interfaces]

Confirmed - Tested Since Memory Clear

Freeze Frame:

Fault Priority: 6

Fault Frequency: 1

Reset counter: 90

Mileage: 153160 km

Date: 2026.04.19

Time: 01:54:32

Voltage terminal 30: 14.5 V

Internal Fault ID: 191

Vehicle speed: 0 km/h

Network management state: normal

Function light in parking brake button: On

Red operating lamp: On

Red warning lamp: OFF

Green operating lamp: OFF

Yellow warning lamp: OFF

Terminal 15 status: On

RWU: not active

DSD: not active

HTR: not active

ECD: not active

ACC requested apply: not active

Auto Adjust: not active

General Inspection Function: not active

Internal Parking Brake state: static

Status of parking brake button: Not operated

Status ParkingBrake left: applied

Status ParkingBrake right: applied

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

Address 55: Headlight Range

Cannot be reached

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

End-------------------------(Elapsed Time: 04:10)--------------------------

------------------------------12 Faults Found------------------------------

1 hour ago, JiMbLeFiSh said:

New battery installed, 3ah more than last at 95ah. Battery coded using 19 - CAN gateway (UDS) as module 61 does not appear in the installed module list.

Does that mean the battery is not properly coded to the car?

33 minutes ago, cliffcoggin said:

Does that mean the battery is not properly coded to the car?

Apologies for the confusion. I was able to code the battery through the CAN gateway module using UDS. I changed 1 character in the serial and updated it's recorded capacity from 92ah(old battery) to 95ah for the new one.

I would have coded it with the correct serial number had I not installed and replaced everything in the tyre well. Should have got a photo beforehand.

In that case I suggest the help of an auto electrician is needed.

I'm going to have to get some current flow diagrams and get pokey with the metre it seems 😬🤌🏻

Honestly this screams water ingress damage from that blocked plenum. The random faults over time + worse in wet weather + now no crank all point to corroded wiring/relay board rather than a single module. Bridging relay 645 proves the engine/ECU can run, so focus on why it’s not being powered/commanded properly.

I’d start with the basics: fresh battery (yours is ancient), then pull the plenum fuse/relay board and inspect underneath properly—these rot from the bottom. Check all grounds in that area and continuity on the power/ignition feeds to the ECU. Also inspect CAN wiring near the ECM, corrosion can distort the signal like you’re seeing.

The ride height sensor fault staying after replacement suggests wiring, not the sensor. Same story likely elsewhere.

I wouldn’t jump to ECU replacement yet—more often it’s wiring/relay panel damage from water.

Arnob80, thanks for the heads up on the out of site potential rotting. I will 100% be undertaking a proper electrical diagnosis soon... continuity, power, grounds, resistance/resistance under load. It's going to be a real party :D

I've been a little busy with life up until now but good news, I was able to get the MOT passed today with a bridged relay and clearing all faults with VCDS. Now that's out of the way I can relax about where to park the car legally and dig in with finding the cause.

I'm considering electrical diagnosis as a career avenue. Seems cars now have so much installed and connected that it really is a head scratcher when something goes wrong and honestly, I really enjoy trying to find the root cause.

I will update as soon as I have something to report. Thank you all for your replies and have a most enjoyable bank holiday weekend.

Jimble