What Is a Mechatronic Unit and How Do You Spot a Fault?

The mechatronic unit is the part that manages gear changes in dual-clutch gearboxes (DSG, S tronic, PDK). The name comes from "mechanical" and "electronic": a hydraulic valve body, solenoid valves, sensors and a control board work together inside it.

What does it do?

Based on information from the car's computer it decides which clutch engages and when, which gear is selected and how much hydraulic pressure is applied. A smooth gear change usually means a healthy mechatronic unit behind it.

Fault symptoms

• Jolts, thumps or delays when changing gear
• The gear indicator flashing on the dashboard
• The car not moving, or skipping certain gears
• Limp mode and a gearbox warning light
• Irregular behaviour that gets worse cold or warm

Is every symptom a mechatronic fault?

No. Clutch wear, low or dirty oil, sensor faults and software mismatches produce similar symptoms. Replacing the mechatronic unit without reading the fault codes and checking the oil and operating values can be the wrong decision. Sometimes the problem inside is just a sensor or a solenoid and the repair is smaller in scope.

The repair

The unit is removed, inspected and the necessary parts are renewed; after fitting, the basic settings and adaptation are carried out. The car is then handed back after a road test and a final read-out. We explain the work and part options in advance.