Error Code P0935 is defined as Hydraulic Pressure Sensor Circuit High. 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.

The job of the hydraulic pressure sensor circuit is to relay information to the PCM (powertrain control module) about the available hydraulic pressure within the transmission. This information helps the PCM make adjustments to the transmission (gear) based on different factors, such as the driving conditions, engine load, etc. If the PCM detects a voltage higher than the set specifications in the transmission line pressure sensor circuit, it registers the Error Code P0935.

Common Symptoms

  • Unusual firm shift during low RPM
  • Unusual soft shift when under load at high RPM
  • Low acceleration power (since the vehicle starts at 2nd gear rather than 1st)
  • Engine unable to upshift at speed (PCM locked out the high gears)

Possible Causes

  • Faulty wires or connectors (caused by damage or corrosion)
  • Faulty fuses
  • Defective transmission pressure sensor
  • PCM/TCM problem (rare)

How to Check

Start the diagnosis by connecting the OBD-II error code scanner to retrieve freeze frame data of the code and other trouble codes. If there are multiple codes present, address the codes in the order they appear on the scanner.

Next, reset the codes and restart the vehicle to see if the code comes back. If the code does not return, the problem is either an intermittent error or triggered erroneously.

If the code comes back, proceed with the diagnosis by inspecting the electrical component system further. Check for any damages on the connectors, fuses, and wires. Repair and replace as needed.

Next, check the ground voltage. If there is no ground found, then proceed on checking the hydraulic pressure sensor.

Make sure to reset the trouble code and restart the vehicle each time you replace a component. This will help determine whether the repair has fixed the problem or not.

How to Fix

  • Repair or replacement of faulty or broken connectors, fuses, and wires
  • Replacement of defective hydraulic pressure sensor
  • Replacement of defective PCM or TCM (rare)

When this code happens, the PCM cannot determine the exact hydraulic pressure buildup within the transmission. This can lead to various problems, including drivability issues such as harsh shifting and being locked out of higher gears. However, ignoring this problem for too long can lead to severe internal damage in the transmission.