P0945
Hydraulic Pump Relay Circuit/Open
- Severity
- High
- Driving
- Drive only to a garage
An open circuit or general electrical fault in the hydraulic pump relay circuit. The relay switches power to the pump that provides all the transmission's hydraulic pressure, so if it cannot be controlled the pump will not run and the transmission will eventually have no pressure to work with.
Possible causes
- CommonFailed pump relay
- CommonCorroded relay socket or fuse box connections
- CommonWiring fault between the module and the relay
- PossibleWater ingress into the fuse box
- PossibleBlown fuse
- RareFailed control module driver
What you might notice
- Pump not running
- Transmission will not change gear
- Car will not move
- Transmission warning message
- Check engine light on
What to check, in order
- Swap the relay with an identical one elsewhere in the box and see whether the fault follows it. It is the quickest test available and costs nothing.
- Inspect the relay socket for corrosion, heat damage and spread terminals - a discoloured socket means the relay has been running hot.
- Check the fuse for the pump circuit.
- Check the fuse box for water ingress.
- Check the wiring between the module and the relay.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
P00xxP01xxP02xxP03xxP04xxP05xxP06xxP07xxP08xxP09xxP0AxxP0BxxP0CxxP0DxxP0ExxP0FxxP10xxP11xxP12xxP13xxP14xxP15xxP16xxP17xxP18xxP19xxP1AxxP1BxxP1CxxP1DxxP1ExxP1FxxP20xxP21xxP22xxP23xxP24xxP25xxP26xxP27xxP28xxP29xxP2AxxP2BxxP2CxxP2DxxP2ExxP2FxxP30xxP31xxP32xxP33xxP34xxP35xxP36xxP37xxP38xxP39xxP3AxxP3BxxP3CxxP3DxxP3ExxP3Fxx
Transmission and control modules
P0900P0901P0902P0903P0904P0905P0906P0907P0908P0909P0910P0911P0912P0913P0914P0915P0916P0917P0918P0919P0920P0921P0922P0923P0924P0925P0926P0927P0928P0929P0930P0931P0932P0933P0934P0935P0936P0937P0938P0939P0940P0941P0942P0943P0944P0945P0946P0947P0948P0949P0950P0951P0952P0953P0954P0955P0956P0957P0958P0959P0960P0961P0962P0963P0964P0965P0966P0967P0968P0969P0970P0971P0972P0973P0974P0975P0976P0977P0978P0979P0980P0981P0982P0983P0984P0985P0986P0987P0988P0989P0990P0991P0992P0993P0994P0995P0996P0997P0998P0999