Powertrain, generic (extended)

P2712 Hydraulic Power Unit Leakage

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2712 targets gearboxes whose clutches or shift forks are worked by a separate hydraulic power unit, typically an electric pump that charges a pressure accumulator. Such a system loses pressure only slowly when sealed; if pressure drops faster than expected or the pump has to recharge too often, the controller concludes there is a leak. No manufacturer documents P2712 publicly. The principle is described in Volkswagen's training booklet for the dry seven-speed DSG 0AM: an electric pump fills a 0.2 l gas accumulator, switches off at about 60 bar according to the pressure sensor and restarts near 40 bar. CARB counts automatic transmission controls among the monitored output components. A leaking accumulator, valve or seal can end in lost gears; P0944 covers a general pressure loss of the hydraulic unit.

Likely causes

Leaking or worn pressure accumulator
Internal leakage at valves or seals of the hydraulic unit
External oil leak at housing, lines or connector seals
Implausible pressure sensor signal

Symptoms

  • Hydraulic pump running often or for long periods
  • Gears not engaging or delayed engagement
  • Gearbox warning and emergency mode

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€400–4,500
Time2–10 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

hydraulic pumpaccumulatorvalve body seals

Related codes

P0944P2711P0868P0C29

References: law.cornell.edu, static.nhtsa.gov.