Hydraulic Power Unit

The electric pump and accumulator that supply an automated manual or dual-clutch gearbox with the pressure to move things — the clutch actuators and the gear selection actuators. A separate system from the transmission's own fluid pressure, with its own pump, its own accumulator and often its own fluid, and confusing the two sends a diagnosis to the wrong place entirely. The accumulator stores pressure so the pump need not run constantly, which makes how long it holds pressure a health measurement of the whole circuit: a system that bleeds down in seconds has a leak, the pump then runs almost continuously to compensate, and that constant running is what eventually destroys it. A frequently running gearbox pump is a symptom worth acting on.

Also known as: hydraulic pump, gearbox pump, accumulator, hydraulic unit, power pack, dsg pump, actuation pump

Referenced by 14 codes

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Codes involving this component (14)

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