The Audi A4 automatic transmission (variator) control unit, also known as the electronic transmission control unit (ECU), performs the following functions:
* Shift Control: Determines the timing and order of gear shifts depending on driving mode, engine speed, load and other factors.
* CVT Monitoring: Monitors CVT parameters such as gear ratio, temperature, oil pressure, etc. to ensure correct operation.
* Overload Protection: Shuts down the transmission or puts it into emergency mode in the event of overheating or other malfunctions.
* Diagnostics and self-diagnosis: Identifies and stores trouble codes that can be read using diagnostic equipment.
* Adaptation to driving style: Optimizes transmission performance according to the driver’s habits and preferences.
* Torque Limits: Protects transmission components from excessive torque, such as during hard acceleration.
* Communication with other components: Exchanges data with other vehicle control units such as the engine, instrument panel and stability control system.
Location:
The automatic transmission control unit is usually located in the engine compartment on or near the engine block.
Original part numbers for Audi A4 with CVT:
* 0B5 927 156 H – until 2006
* 0B5 927 156 K – from 2006