Delta Pressure
WARNING: This page is about a different car, the 2008 Suzuki Swift +, 2008 Pontiac Wave, and 2008 Chevrolet Aveo. However, it is still accessible from the selected car via links, so may be relevant.
While the tire is stationary and when the air pressure changes rapidly by at least 1.2 psi, the sensor will transmit a Learn Mode-Pressure Triggered message. Inflating or deflating the tire until a horn chirp is heard will ensure that the learn happened.