Hi all

Audi a6 c7 6sp manual tdi 2.0 2015/6

I got start stop system fault contract workshop, scanned the car and got clutch error for start and interlock error too, replaced the clutch but still nothing is happening, anyone else had same issue what turned out to be the culprit? Wires? Which i am pointing at atm

The pictures below is showing bits whith clutch pressed goes from 1 to 0 and intetlock should go from 0 to 1 but there is no change in bit for interlock

 

Thanks 

Edited December 10, 2025Dec 10 by demiari

I don't understand why you have changed the clutch when it is only a switch that is faulty.

Sorry typo replaced the clutch master cylinder with the switch integrated onto it and nothing happened, funny enough though the interlock bit was flicking between 0 to 1 intermittently with the new switch that way i was able to start her after numerous tries but then the bit for interlock remains at 0 constantly now and wont start any clue 

58 minutes ago, demiari said:

Sorry typo replaced the clutch master cylinder with the switch integrated onto it and nothing happened, funny enough though the interlock bit was flicking between 0 to 1 intermittently with the new switch that way i was able to start her after numerous tries but then the bit for interlock remains at 0 constantly now and wont start any clue 

If you search the A6 C7 and the A4 parts of the forum there are more than enough posts on the subject, it probably is a wiring fault and from memory a couple of them just bypassed the switch just to get a running vehicle, you might have to go back a couple of years but if you get stuck ask Gareth [Magnet] and he has an uncanny knack of pointing people in the right direction.

Steve.

3 hours ago, Stevey Y said:

If you search the A6 C7 and the A4 parts of the forum there are more than enough posts on the subject, it probably is a wiring fault and from memory a couple of them just bypassed the switch just to get a running vehicle, you might have to go back a couple of years but if you get stuck ask Gareth [Magnet] and he has an uncanny knack of pointing people in the right direction.

Steve.

Ive looked everywhere there is very limited info, i get that clutch switch has been discussed but this one is different as i can see clutch is being picked as it changes from 1 to 0 when depressed but interlock just stays the same, the error i am getting for interlock could anyone interpret it please see photo

18 hours ago, demiari said:

Ive looked everywhere there is very limited info, i get that clutch switch has been discussed but this one is different as i can see clutch is being picked as it changes from 1 to 0 when depressed but interlock just stays the same, the error i am getting for interlock could anyone interpret it please see photo

Hi any chance you can post the picture of the fault readings a bit bigger please as its blurred and I can't even see what it says on full magnification.

Steve.

Hi Stevey

This is text

I also forgot to mention 3 weeks ago windows were opened i must have pressed the button and opened all windows and it was raining all night centre console was wet and floors were wet but i drove it and turned on high heat with ac dried them up but wondering if it is a corrosion under floor or something.

Fault Status: 00000001

Fault Priority: 2

Fault Frequency: 1

Mileage: 387123 km

Date: 2025.11.27

Time: 22:04:28

 

Engine RPM: 829.00 /min

Normed load value: 36.9 %

Vehicle speed: 0 km/h

Coolant temperature: 74 °C

Intake air temperature: 52 °C

Ambient air pressure: 1000 mbar

Voltage terminal 30: 14.320 V

Unlearning counter according OBD: 40

Starter control: Interlock or P/N-signal-Bits 0–7: 65

Brake actuation status-Bits 0–7: 65

Selector lever position-Bits 0–7: 0

Transmission neutral position sensor: adaptation status-Bits 0–7: 2

Engine status: COENG_RUNNING

Engine status-Test_Program_Co_eng st @ COMPU VERB UBYTE3: 3

1 hour ago, demiari said:

Hi Stevey

This is text

I also forgot to mention 3 weeks ago windows were opened i must have pressed the button and opened all windows and it was raining all night centre console was wet and floors were wet but i drove it and turned on high heat with ac dried them up but wondering if it is a corrosion under floor or something.

Fault Status: 00000001

Fault Priority: 2

Fault Frequency: 1

Mileage: 387123 km

Date: 2025.11.27

Time: 22:04:28

 

Engine RPM: 829.00 /min

Normed load value: 36.9 %

Vehicle speed: 0 km/h

Coolant temperature: 74 °C

Intake air temperature: 52 °C

Ambient air pressure: 1000 mbar

Voltage terminal 30: 14.320 V

Unlearning counter according OBD: 40

Starter control: Interlock or P/N-signal-Bits 0–7: 65

Brake actuation status-Bits 0–7: 65

Selector lever position-Bits 0–7: 0

Transmission neutral position sensor: adaptation status-Bits 0–7: 2

Engine status: COENG_RUNNING

Engine status-Test_Program_Co_eng st @ COMPU VERB UBYTE3: 3

Hi right now we are getting somewhere, if the floor has been soaked that could well cause a problem as there are multiple modules under the carpet on the drivers side which if exposed to moisture will play up its not corrosion but moisture on the plugs that cause most problems as moisture causes the current to swap between the pins inside, pull up the carpet and have a look, pull the plugs and give both male and female sides a generous coat of WD40, the problem with the carpets is they are not waterproofed at the back, a guy who does our local mobile valeting told me BMW and MERC are ok when wet vacuumed as they have a waterproof membrane under the carpet, Audi on the other hand do not, they also have a vast range of comfort module units which are daisy chained into the wiring loom, believe me when I say the biggest nightmare on A6/A4 2013 on is the wiring as it tends to be very fragile where water is involved, therefore if you get at it now I dont think its a disaster as the fault frequency is only on 1.

Steve.

5 minutes ago, Stevey Y said:

Hi right now we are getting somewhere, if the floor has been soaked that could well cause a problem as there are multiple modules under the carpet on the drivers side which if exposed to moisture will play up its not corrosion but moisture on the plugs that cause most problems as moisture causes the current to swap between the pins inside, pull up the carpet and have a look, pull the plugs and give both male and female sides a generous coat of WD40, the problem with the carpets is they are not waterproofed at the back, a guy who does our local mobile valeting told me BMW and MERC are ok when wet vacuumed as they have a waterproof membrane under the carpet, Audi on the other hand do not, they also have a vast range of comfort module units which are daisy chained into the wiring loom, believe me when I say the biggest nightmare on A6/A4 2013 on is the wiring as it tends to be very fragile where water is involved, therefore if you get at it now I dont think its a disaster as the fault frequency is only on 1.

Steve.

Thank you Stevie,

Ill check that tomorrow and get back to you, ill also have a look at the module in the boot 

Will report back 

Thanks

1 minute ago, demiari said:

Thank you Stevie,

Ill check that tomorrow and get back to you, ill also have a look at the module in the boot 

Will report back 

Thanks

Hi yes anything that looks like its sweating is bad news.

Steve.

Ended up in Audi dealer 760e, crimped 4 wires of the clutch switch and she is good again now! Cant tell how the wire there ended up being damaged as there is no movement there at all but probably due to vibrations anyway she is back eventually