There are two types of system one is you can do it from the ABS System and the other one id you do it from Steering Asst Module..............How did this steering light come ON..............? did you do any work on this vehicle..............? Also you need to diagnose first the ABS and Steering Asst System to see if there are no any fault code stored in any system............If there are any faults than the system will not let you do the Angle Sensor Calibrations............

 I think that steering angle sensor calibration won't solved the problem of heavy steering.