P0942 code meaning
Hydraulic Pressure Unit
Powertrain system Generic code P09xx codes Check engine light
What P0942 means
General fault of the unit that generates and stores hydraulic pressure for an automated gearbox or its auxiliary oil supply: motor-driven pump, accumulator and pressure control. Toyota sets P0942 on the 2001 to 2005 MR2 Spyder sequential gearbox together with the SMT warning light and a buzzing pump, or with gears that can no longer be changed; fluid seeping from the reservoir cap or the seal of the hydraulic power unit is a known cause, fixed with new seal rings. Ferrari reads P0942 on its DCT differently, as system pressure command signal too low. CARB requires functional checks of transmission outputs. P0943 and P0944 are the cycling and pressure-loss faults, P0945 to P0948 the pump control circuit.
P0942 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 6 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0942
- Transmission or gearbox warning light on
- Pump buzzing or running for long periods
- Gears cannot be changed or shifts are delayed
- Auto stop-start disabled or engine restarts immediately
Common causes of P0942
- Most likelyFluid loss at the reservoir cap or hydraulic power unit seals
- PossibleWorn pump motor or faulty pump relay
- PossibleDamaged wiring, connectors or power supply of the pump
- Less likelyTransmission control module fault
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hydraulic pressure unitTCM
What each part of P0942 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. |
| 42 | The exact fault in that area. |
What to do next
- Note P0942 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 P0942
What does P0942 mean?
P0942 means "Hydraulic Pressure Unit". General fault of the unit that generates and stores hydraulic pressure for an automated gearbox or its auxiliary oil supply: motor-driven pump, accumulator and pressure control. It is a generic code, so it means the same on every make.
Is it safe to drive with P0942?
Drive gently and only to a workshop. With P0942 the car can go into limp mode (reduced power) to protect itself.
Will P0942 fail an emissions test?
Yes, it can. P0942 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 P0942 to fix?
Difficulty: hard. A typical repair takes 1 to 6 hours of work. This is a job for a workshop.
Will P0942 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.