P0945Hydraulic Pump Relay/Control Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- The control module drives the motor of the hydraulic pump through a relay or a direct output. This code reports a general circuit fault or an open in that control path, so the pump cannot be switched reliably. No manufacturer documents this exact code publicly. The layout is shown by a ZF patent for an automated gearbox, in which a motor-driven pump draws oil from a reservoir and charges a pressure accumulator behind a one-way valve, with shut-off valves feeding the shift cylinders. CARB requires circuit checks on transmission outputs. P0946 is the plausibility fault, P0947 and P0948 low and high; P094E covers the pump supply instead of the control side. Without the pump the gearbox soon runs out of pressure.
- What you may notice
- Warning light on
- Pump does not run, pressure is not built
- Gears cannot be changed or auto stop-start disabled
- Likely causes
- LikelyPump relay coil open or relay not seated
- PossibleOpen control wire or loose terminal between module and relay
- RareFailed output stage in the control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.