Hydraulic Pressure Unit Loss of Pressure
What it means
P0944 means the transmission's hydraulic pressure unit has lost pressure — the system can't maintain the line pressure the transmission needs to engage and hold gears. The engine still starts, but the transmission may shift poorly, slip, or fail to move the car, and low pressure can cause rapid internal damage. Check fluid level and leaks first; beyond that it usually points to the pump, valve body, or a stuck solenoid.
Can I keep driving? Stop driving soon — real loss of hydraulic pressure can leave the transmission unable to shift or move the car and can cause internal damage.
Common symptoms
What you'll notice
- Check-engine light on
- Transmission shifts poorly or not at all
- Transmission slips or fails to engage a gear
- Harsh or delayed engagement
- Transmission may drop into limp mode or lose drive
Common causes
Most likely first
- Low transmission fluid levelLikely
- Failed hydraulic pressure unit / pumpCommon
- Internal leak, worn valve body, or stuck pressure solenoidCommon
- Damaged wiring or connector in the circuitLess often
- Failed transmission control module (rare)Less often
How to diagnose & fix
Work through it in order
- Check transmission fluid level and look for leaks before anything else.
- Read freeze-frame data and note when pressure is lost.
- Verify actual line pressure with a gauge to confirm a real loss vs. a sensor fault.
- Inspect the pump/pressure unit, solenoids, and valve body for internal leakage or failure.
- Repair or replace the failed hydraulic component; stop driving until pressure is restored.
FAQ
Quick answers
Is it safe to drive with P0944?+
Can I just clear P0944?+
Related codes
Often seen with P0944
Read & clear P0944 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.