P0946: Hydraulic Pump Relay/Control Circuit Range/Performance
What to do
If the relay has been replaced before, or has failed early, ask whether the pump has been running unusually often — burnt contacts are usually a symptom of that rather than a fault in their own right, and replacing the relay alone will not last.
What this code means
The pump relay is responding, but not as commanded — closing late, releasing slowly, or reporting a state that does not match the instruction. Burnt contacts are the usual reason: the pump motor draws a substantial inrush current every time it starts, and on a system that has been cycling too often those starts number in the tens of thousands rather than the thousands.
That gives a useful chain to follow. Relay contacts burnt prematurely are evidence that the pump has been running far more than it should, which points back at a leak rather than at the relay being a poor part.
Likely causes
Start here
- Faulty hydraulic pump relay · easy
- Welded relay contacts · easy
- Hydraulic system leak · specialist
Less common
- Corroded or loose connector · easy
- Faulty hydraulic power unit · specialist
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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