Error Code P0944 is defined as Hydraulic Pressure Unit Loss of Pressure. This is a generic trouble code, meaning it applies to all vehicles equipped with the OBD-II system, especially those made since 1996 up to the present. Of course, specifications on the definition, troubleshooting, and repairs vary from one make and model to another.
It is most common among Dodge and Jeep vehicles but is also applicable in some manufacturers such as Volkswagen.
When this code appears, it means the Powertrain Control Module (PCM), also known as the vehicle’s computer, has determined a significant drop in the transmission pressure, and the pump lost its prime and failed the prime test. The prime test is done when the transmission slips while in any gear that indicates forward and has no pressure situation from all pressure switches.
Depending on the severity of the condition, this code may exhibit one or more symptoms, including:
- Check engine light activated
- Delayed transmission shifting
- Transmission unable to shift
Since this code refers to loss of transmission pressure and prime at the pump, multiple factors could contribute to the problem, including:
- Failed transmission pump
- Blockage at the transmission fluid channel
- Loose transmission cooler return filter
- Dirty or Not enough transmission fluid
- Chipped or improperly installed transmission filter (or seal)
- Stuck main regulator valve
How to Check
Start the diagnosis by connecting the diagnostic scanner to the vehicle. Check the codes stored before clearing. Then, take the vehicle for a test drive to find out if the code resets.
Using the scan tool, conduct a shift lever position test. If it passes the shift lever position test, test the pressure in the transmission line. Use the scan tool while the engine is running and the transmission set at park position. The transmission should be at operating temperature for this test to be accurate. Depending on the result of this test, you may need to test the transmission line pressure for both drive and reverse transmission positions using the scan tool.
Next, check for any signs of leakage. Replace as needed.
If there are no leakages, you may need to replace the pump.
You may also remove the transmission fluid pan to check the filter for any signs of wear and tear and damage.
How to Fix
- Changing transmission fluid
- Transmission flush
- Replacement of defective pump
- Replacement of clogged or damaged transmission filter
- Replacement of damaged internal seal or topping off fluid
- Replace, rebuild or install remanufactured transmission
One of the common mistakes in diagnosing this code is not allowing the transmission to run at normal operating temperature before testing, as this could give inaccurate or false negative results.
This error code is quite serious; it renders the vehicle inoperable since the transmission will not engage. Thus, it should be addressed as soon as possible as it may cause further damage to the transmission.