Conditions for Setting the DTC
WARNING: This page is about a different car, the 2017 GMC Canyon and 2017 Chevrolet Colorado. However, it is still accessible from the selected car via links, so may be relevant.
B123E 01
The radio detects an open/high resistance or short to voltage on the radio controls key signal circuit
B123E 02
The radio detects a short to ground on the radio controls key signal circuit