One of the big issues with various Audi DSG gearboxes has undoubtedly been the mechatronic unit. While there were improvements made from 2012 on, it continues to be a concern with owners. This is particularly true of the Borg Warner DL501 which as far as I know, can be found in cars dating back to 2009, 2010.
It’s a fairly complicated, complex device which, in the past, was replaced as a whole unit. Audi has made several updates over the years and they have become more reliable. The newer the gearbox, the more reliable they seem to be. There was a major improvement post-2012 but there are failures seen on various Audi models from the A4 to the S7. The DL501 is found in the A4, A5, A6, S4, S5, RS5, S6 and S7. There are minor differences in each model from the clutch flywheel to the clutch plate size and internal gearing on the mechanical side.
Audi uses a liquid to liquid transmission cooler for the ATF side on most models and years. The cooling liquid is the radiator coolant. It works to heat up the fluid and then cool it once the internal fluid becomes hotter than the radiator coolant. Personally, I find it to be woefully inadequate and it doesn’t allow the clutch cooling circuit to shed heat fast enough and tends to run the ATF fluid at a high enough temp that there’s not much margin between adequate performance and overheating safeguards.
The mechatronic has numerous solenoids and sensors. Here are a few and what they do.
-N433 controls shift fork for gears 1-3
-N434 controls shift fork for gears 7-5
-N435 clutch control solenoid clutch pack 1
-N436 controls pressure for the clutch 1 pack (odd gears)
-N437 controls 2nd gear and reverse
-N438 controls the shift fork mechanism, gears 4-6
-N439 Clutch control solenoid clutch pack 2
-N440 for the clutch 2 pack, pressure regulator (even gears)
-N471 is for cooler flow, clutch pack cooling
-N472 is the main pressure control solenoid
-G193 is the pressure for clutch pack1
-G194 is the pressure sensor for clutch pack 2
-G487 is a gear position distance sensor for 2nd and reverse
-G488 Gear position distance sensor for 1-3
-G489 Gear position distance sensor for 5-7
-G490 Gear position distance sensor for 4-6
-G509 Clutch oil temp sensor
-G641 Transmission input speed sensor
-G612-Transmission input speed sensor
-G632-Transmission input speed sensor 1
G-676 Drive position sensor
There are two PCB’s and one electronic module which is, I’m assuming, the main TCU for the transmission. All are internal and cooled/lubed by the ATF fluid circuit.
Resistance for each solenoid
N433 5 Ohms
N434 5 Ohms
N435 15 Ohms
N437 5 Ohms
N438 5 Ohms
N439 15 Ohms
N471 4.5 Ohms
N472 4.5 Ohms
In addition, there are two valves.
-Pressure regulating valve
-Clutch cooling control valve