Error Code P0867 is referred to as Transmission Fluid Pressure. This is a generic trouble code, meaning it applies to vehicles equipped with the OBD-II system, particularly those made from 1996 up to present. Specifications on the definition, troubleshooting, and repairs may vary depending on the manufacturer, year model, and powertrain configuration.

The Transmission Control Module (TCM) works by monitoring the actual line of pressure continuously and compares the results to the desired line pressure. If the difference between the desired and the actual line pressure is 10 psi (.7 kg/cm2) or higher, then this trouble code will be stored.

The transmission defaults to open loop line pressure control, which results in a fixed solenoid duty cycle. The duty cycle changes slightly depending on current gear and temperature.

Common Symptoms

  • Check engine light on

Possible Causes

  • Dirty or low transmission fluid
  • Defective transmission fluid pressure sensor
  • Open or shorted transmission fluid pressure sensor harness
  • Poor electrical connection in transmission fluid pressure sensor

How to Check

First and foremost, check the transmission fluid level. Make sure the vehicle has enough transmission fluid and adjust as necessary. In some cases, the fluid level doesn’t show on the dipstick, especially if the transmission temperature is less than 50°F (100°C), even if the transmission fluid level is adequate.

Next, check the connections and look for signs of damages in the connector or faulty wirings.

If both fluid level and wirings are fine, you may suspect a faulty TCM.

Next, check if the plugged transmission fluid filter, pressure sensor calibration, intermittent wire or connector problem, and internal transmission problem.

Also, check the pressure sensor connection, and for open or shorted to ground (or shorted to voltage) pressure sensor circuit.

If everything checks out fine, then you can suspect a faulty TCM (rare).

 How to Fix

  • Flush out and replace the old and dirty transmission fluid
  • Fill the transmission fluid to an adequate level
  • Repair or replace open or shorted wiring harness and connectors in the fluid pressure sensor
  • Check for bent, broken, corroded, or pushed out connector pins, repair or replace as needed
  • Replacement of TCM (rare)

This can be a tricky problem to troubleshoot and repair. Nevertheless, it must be addressed as soon as possible.