Haldex Controller

The Haldex control unit is the ECU mounted on the coupling itself. It reads wheel speed, throttle and stability-control data and decides how much torque goes to the second axle. When it fails you typically get a permanent AWD warning light, no drive to the rear axle at all, and a stored communication or open-circuit fault that will not clear. Eco Torque stocks control units for Audi, SEAT, Skoda and VW.

Control units are not interchangeable between generations or part numbers — 0AY 907 554 J, 0AY 907 554 L and 0CQ 907 554 J are all different units. Check the number printed on the unit fitted to the car before ordering, and be aware that a replacement normally needs coding to the vehicle. Before condemning the controller it is worth ruling out the pump and a blocked filter, which produce similar symptoms far more often. Not sure which parts you need? Send us your registration or VIN and we'll help.

Fits: Audi · SEAT · Skoda · Volkswagen