22poundnote
03-09-2023, 10:31 AM
Good evening all,
I am looking for some help/advice from the community with regard to my current issue(s). I have a 2012 S6 4.0tfsi tt, 2 weeks ago I started getting a "Gearbox malfunction: you can continue driving." error on the dash, it happened once and disappeared straight away so thought nothing of it. 2 days later I get the same error but this time it puts the car into reduced torque mode and the little yellow cog remains so, naturally, I scan the car and get a fault in 02-Auto Trans coming up as "Transmission Fluid Temperature Sensor 2 " implausible signal, a further look into the address shows that the sensor is reading 140*c when the car is cold and the rest of the sensors read 11*c. This sensor is on the PCB inside the TCU which is attached to the mechatronic unit. I decide to have it removed and sent off to ECU testing to be repaired in a week or so when I have the time. A few days later, before I have had time to carry out the repair and I get in the car and start it as usual and now I get multiple errors/malfunctions; ABS fault, ESP fault, Audi headlight assist malfunction, TPMS malfunction, sport diff malfunction, air suspension malfunction, gearbox malfunction, etc.. I immediately think electrical/low voltage issue and replace the battery as upon inspection I find the battery is the one the car left the factory with in 2012. Not the issue, I do more research on the forums and find some people have similar issues with ABS sensors causing this kind of issue, checked on VCDS and all values look fine, every sensor increases/decreases in value the same when driving so rule out ABS sensors. Do some more digging and find this gearbox has a plagued connector on the side which gets coolant/water in it and it gets corroded and can cause an issue similar to this. I immediately call a friend and get the car to him (at this point the gearbox does not know what gear it is in and I have to have it recovered) and put it on the ramp, the connector does indeed have water/coolant ingress and corrosion. We clean it out and connect it all back up, clear the codes and it all comes back as if it never got cleared. I pull my hair out and look at some wiring diagrams online and find that there is 2 fuses for the transmission in fuse box -SA- in fuse holder A, a 15a in slot 1, and a 5a in slot 12, checked both today and they are fine [headbang]. We checked that power is going to the TCU by checking the pins on the aforementioned connector and it's all good. I think the next step is to get the whole mechatronic unit out and sent off for refurbishment by ECU testing and put it back in. However, is there anything else I can check or diagnose this further at this point or am I just shit out of luck?
I apologise for the long post but felt the need to include all relevant info, below are 2 scans, the first is before the TCU stopped communicating and the second is after it blocked me.
Any help/advice is/will be much appreciated.
Thanks
22Poundnote
I am looking for some help/advice from the community with regard to my current issue(s). I have a 2012 S6 4.0tfsi tt, 2 weeks ago I started getting a "Gearbox malfunction: you can continue driving." error on the dash, it happened once and disappeared straight away so thought nothing of it. 2 days later I get the same error but this time it puts the car into reduced torque mode and the little yellow cog remains so, naturally, I scan the car and get a fault in 02-Auto Trans coming up as "Transmission Fluid Temperature Sensor 2 " implausible signal, a further look into the address shows that the sensor is reading 140*c when the car is cold and the rest of the sensors read 11*c. This sensor is on the PCB inside the TCU which is attached to the mechatronic unit. I decide to have it removed and sent off to ECU testing to be repaired in a week or so when I have the time. A few days later, before I have had time to carry out the repair and I get in the car and start it as usual and now I get multiple errors/malfunctions; ABS fault, ESP fault, Audi headlight assist malfunction, TPMS malfunction, sport diff malfunction, air suspension malfunction, gearbox malfunction, etc.. I immediately think electrical/low voltage issue and replace the battery as upon inspection I find the battery is the one the car left the factory with in 2012. Not the issue, I do more research on the forums and find some people have similar issues with ABS sensors causing this kind of issue, checked on VCDS and all values look fine, every sensor increases/decreases in value the same when driving so rule out ABS sensors. Do some more digging and find this gearbox has a plagued connector on the side which gets coolant/water in it and it gets corroded and can cause an issue similar to this. I immediately call a friend and get the car to him (at this point the gearbox does not know what gear it is in and I have to have it recovered) and put it on the ramp, the connector does indeed have water/coolant ingress and corrosion. We clean it out and connect it all back up, clear the codes and it all comes back as if it never got cleared. I pull my hair out and look at some wiring diagrams online and find that there is 2 fuses for the transmission in fuse box -SA- in fuse holder A, a 15a in slot 1, and a 5a in slot 12, checked both today and they are fine [headbang]. We checked that power is going to the TCU by checking the pins on the aforementioned connector and it's all good. I think the next step is to get the whole mechatronic unit out and sent off for refurbishment by ECU testing and put it back in. However, is there anything else I can check or diagnose this further at this point or am I just shit out of luck?
I apologise for the long post but felt the need to include all relevant info, below are 2 scans, the first is before the TCU stopped communicating and the second is after it blocked me.
Any help/advice is/will be much appreciated.
Thanks
22Poundnote