P0947Hydraulic Pump Relay/Control Circuit Low
- 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 voltage on the control line of the hydraulic pump relay or driver is lower than the module expects for the commanded state. Usually the line is shorted to ground or the relay coil is shorted, so the output may be overloaded and the pump runs when it should not, or the driver shuts down. No manufacturer documents this exact code publicly. The hydraulic unit it belongs to, a motor-driven pump that charges an accumulator for the shift and clutch cylinders of an automated gearbox, is described in a ZF patent. CARB requires circuit checks on transmission outputs. P0948 is the high counterpart, P0945 the open fault, P0946 plausibility. Pressure supply for shifting may fail.
- What you may notice
- Warning light on
- Pump runs continuously or not at all
- Gearbox in limp mode or stop-start disabled
- Likely causes
- LikelyRelay control wire chafed and shorted to ground
- PossibleShorted relay coil
- RareDamaged 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.