Error Code P0942 is defined as Hydraulic Pressure Unit. 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.

Error Code P0942 is commonly found in vehicles manufactured by Chrysler or Volkswagen. However, it can also be seen in other vehicle brands like Ford.

One of the Transmission Control System (TCM) functions is to control the line pressure electronically. The Line Pressure Sensor (LPS) measures line pressure. The desired pressure is constantly compared to the actual line pressure, which is regulated by electronically changing the duty cycle of Pressure Control Solenoid (PCS).

Based on the inputs from both the engine and transmission, the TCM then analyzes the desired line pressure. The Torque Based Line Pressure, the calculated torque input to the transmission, is used as the primary input for the desired line pressure calculation. The TCM monitors the Hydraulic Pressure sensor and sets the error code when the said sensor doesn’t meet the factory specifications.

When this code is present, there is a significant problem with the transmission pump that creates the hydraulic pressure required for the transmission to work and ultimately drives the wheels.

Common Symptoms

  • Transmission unable to shift
  • Delayed shifting

Possible Causes

  • Dirty of low transmission fluid
  • Blocked or loose transmission cooler or shifter
  • Shift lever position
  • Faulty transmission oil pump
  • Blockage of fluid inside the transmission or valve body
  • Stuck transmission regulator valve

How to Check

Start the diagnosis by checking the transmission pump’s operation using a transmission line pressure test.

Next, look for transmission leaks. Make sure you also check the condition of the transmission fluid and look for signs of internal damage.

How to Fix

  • Refilling and replacement of transmission fluid
  • Replacement of transmission cooler lines filter
  • Transmission pump replacement
  • Transmission regular pump replacement
  • Transmission regular valve replacement
  • Replacement, rebuilding, or installation of the remanufactured transmission

Since the problem causes the transmission not to work correctly, this error code is quite a serious problem. Thus, it must be addressed as soon as possible to avoid further damage and more expensive repairs.