What Does P0944 Mean?
DTC P0944 indicates the hydraulic pressure unit has experienced a complete or near-complete loss of hydraulic pressure. The TCM detects that pressure has fallen below the critical minimum threshold required for clutch engagement and gear selection. This is a serious fault that typically results in an inability to shift gears or move the vehicle. Immediate attention is required as this represents a fundamental failure of the transmission actuation system.
Safety Warning
Loss of hydraulic pressure means the transmission cannot engage gears or control the clutch. The vehicle may be completely undrivable or could lose drive unexpectedly while moving. Do not attempt to drive the vehicle; have it towed to a repair facility.
Common Causes
30%
Severe hydraulic fluid leak (blown hose, cracked fitting, or seal failure)
25%
Hydraulic pump motor failure (seized, burnt out, or disconnected)
20%
HPU relay or fuse blown, preventing pump operation
15%
Complete hydraulic fluid depletion from the reservoir
10%
Pressure relief valve stuck fully open
Diagnostic Steps
1
Step 1: Immediately check the hydraulic fluid level in the HPU reservoir. If empty, inspect underneath the vehicle for a major fluid leak and identify the source before adding fluid.
2
Step 2: Verify the HPU relay and fuse are intact. Listen for the pump motor activating when the ignition is turned on or when commanded via scan tool.
3
Step 3: If the pump does not run, check for power and ground at the HPU motor connector. Measure voltage during commanded operation to confirm the relay is switching correctly.
4
Step 4: If the pump runs but no pressure builds, inspect for a catastrophic leak. Check all hydraulic lines, fittings, the clutch slave cylinder, and gear selector actuators for fluid discharge.
5
Step 5: If no external leak is found and the pump runs, the HPU may have internal pump failure or a stuck-open pressure relief valve. The unit typically requires replacement.
6
Step 6: After repair, refill and bleed the hydraulic system per manufacturer procedure. Clear codes, perform TCM adaptation, and verify proper pressure buildup and gear selection.
Estimated Repair Cost
$500 - $3,000
Parts + labor, varies by vehicle and location
DTC P0944 indicates the hydraulic pressure unit has experienced a complete or near-complete loss of hydraulic pressure. The TCM detects that pressure has fallen below the critical minimum threshold required for clutch engagement and gear selection. This is a serious fault that typically results in a...
The most common cause of P0944 (Hydraulic Pressure Unit Loss of Pressure) is: Severe hydraulic fluid leak (blown hose, cracked fitting, or seal failure)
Typical repair costs for P0944 range from $500 to $3,000, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Loss of hydraulic pressure means the transmission cannot engage gears or control the clutch. The vehicle may be completely undrivable or could lose drive unexpectedly while moving. Do not attempt to drive the vehicle; have it towed to a repair facility.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0944 to identify the root cause.
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Quick Info
Category
Powertrain
System
Transmission / Clutch Hydraulic System
Difficulty
Type
Generic (SAE)
Recommended Tools
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