P0946Hydraulic Pump Relay/Control Circuit Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- The pump control circuit is electrically intact, but its behaviour does not match the command, for example a pump that keeps running after being switched off, or one that switches but is not followed by the expected feedback. No manufacturer documents this exact code publicly. In the hydraulic unit of an automated gearbox, as shown in a ZF patent, the pump only has to run until the accumulator is charged; a relay that sticks or switches late upsets that cycle. CARB requires functional checks on transmission outputs. P0945 is the general circuit or open fault, P0947 and P0948 the low and high faults, P094B a pump stuck on regardless of the relay. A pump that never stops drains the battery and wears quickly.
- What you may notice
- Pump keeps running after switch-off
- Warning light on
- Auto stop-start not available
- Battery discharged after parking
- Likely causes
- LikelyRelay contacts welded or sticking
- PossiblePump supply or control wire shorted to battery voltage
- RareFaulty pump state feedback or 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.