The pump runs but the expected hydraulic pressure does not build or collapses. Stellantis names it Loss of Hydraulic Pump Prime: a 2023 STAR case lists it with P0868 and a slow engagement after the vehicle has stood, both set as the only transmission codes with the MIL on, and the fix was a new transmission; an FCA defect file from 2015 also shows it beside line pressure low. Mercedes uses P0944 on the 722.9 automatic with electric auxiliary oil pump for stop-start, as internal fault of that pump; stop-start stops working, and a leaking check valve between converter housing and pump is one cause. Ferrari reads it on its DCT as no system pressure signal with pressure loss. P0943 covers short cycles, P0868 low fluid pressure.
Medium severity. Can I keep driving?If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
Symptoms
- Check engine or transmission warning light on
- Slow engagement after the vehicle has been parked
- Auto stop-start not available or engine restarts at once
- Slipping, no drive or limp mode
Most likely causes
- Pump loses prime (air drawn in through filter, seal or strainer pipe)
- Blocked oil strainer or suction tube
- Worn or failed pump (mechanical or electric)
- Leaking check valve or internal leak in the valve body
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- It can trigger limp mode.
- It affects emissions.
What each character of P0944 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 9: Transmission
- 44: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0944?
If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
What causes code P0944?
The most common causes are: pump loses prime (air drawn in through filter, seal or strainer pipe); blocked oil strainer or suction tube; worn or failed pump (mechanical or electric).
Related codes
- P0942Hydraulic Pressure Unit
- P0943Hydraulic Pressure Unit Cycling Period Too Short
- P094CHydraulic Pump Performance/Stuck Off
- P0868Transmission Fluid Pressure Low
Sources
- static.nhtsa.gov: MC 10243164 9999
- static.nhtsa.gov: INRD PE15025 64266P
- static.nhtsa.gov: MC 10205289 9999
- static.nhtsa.gov: MC 10168599 0001
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.