Code No. C121A Steering angle sensor initialization: Operation
WARNING: This page is about a different car, the 2014 Mitsubishi Outlander. However, it is still accessible from the selected car via links, so may be relevant.
Steering wheel sensor stores the neutral position learned by scan tool. When the neutral position has not been stored in the steering wheel sensor yet, the steering wheel sensor outputs the signal indicating that it does not have neutral position.