With the right TPMS tools and knowledge, TPMS relearn procedures can be easy to service. However, failing to perform a complete TPMS relearn procedure can result in failure of tire pressure readings and TPM system failure. Based on customer phone calls and emails to tech support, the most difficult relearn process is Toyota and Lexus, which requires an OBD relearn procedure. An advanced TPMS diagnostic scan tool, such as the VT56 and VT55 is required to perform an OBD relearn.

Sometimes, the relearn procedure fails even after the steps are properly performed because of the “SET” button, which is located below the steering wheel or in the glove box in some Toyota models.  When the button is pressed, the system tries to locate the sensor ID’s that are already stored. The “SET button” can be used when performing a tire rotation that have different tire pressures in the front and rear, changing or adjusting the tire pressure, or changing tire size, or when tires are replaced.  However, when replacing a sensor or installing a second set of wheels, an OBD relearn must be performed. The OBDII module connection will program the new sensor ID numbers into the vehicle’s ECU. Then, the relearn procedure can be performed.

If the “SET” button is pushed, and a relearn must be performed, the ECU must be unlocked in order for the relearn procedure to work correctly. An advanced TPMS scan tool, such as the VT56, has an “UNLOCK ECU” button under the service TPMS menu that can help turn the button “OFF”. After using the “UNLOCK ECU” option within the tool, the relearn procedure can be properly performed using the relearn procedure steps that are explained within the tool.