P094B code meaning
Hydraulic Pump Stuck On
Powertrain system Generic code P09xx codes Check engine light
What P094B means
The hydraulic pump keeps running although the module has switched it off, or it never reaches its cut-out point. Causes are a welded relay or shorted driver, or a pump that cannot reach cut-out pressure because of leakage. No manufacturer documents this exact code publicly. In the pump and accumulator unit of an automated gearbox, described in a ZF patent, the pump should rest once the accumulator is charged. Toyota links a constantly buzzing pump on the MR2 sequential gearbox to fluid loss at the hydraulic power unit, reported under P0942. CARB requires functional checks on outputs. P094C is the opposite fault, P0946 the relay plausibility fault, P0943 the too-short cycle. Battery drain and pump wear follow.
P094B at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P094B
- Pump audible after the vehicle is switched off
- Discharged battery
- Warning light on
Common causes of P094B
- Most likelyPump relay contacts welded closed
- PossibleLeakage or lost accumulator charge keeps pressure below cut-out
- PossibleShorted driver stage or supply wire shorted to battery voltage
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hydraulic pumpHydraulic pump relayTCM
What each part of P094B means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 9 | Area: transmission. |
| 4B | The exact fault in that area. |
What to do next
- Note P094B and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P094B
What does P094B mean?
P094B means "Hydraulic Pump Stuck On". The hydraulic pump keeps running although the module has switched it off, or it never reaches its cut-out point. It is a generic code, so it means the same on every make.
Is it safe to drive with P094B?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P094B fail an emissions test?
Yes, it can. P094B is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P094B to fix?
Difficulty: medium. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will P094B clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.