If car air conditioning system works properly, and error is B1421 the only DTC that is registering, then don't worry.
If you insist upon worrying, then place an LED light 1 foot away from the solar sensor to clear the code, and see if it stays away. You need a light that will cast heat upon the solar sensor.
If the code goes away under that condition, then don't worry as the sensor and AC amplifier are working properly.
B 1400 is for bad O2 sensor
B 2318 is for HEV voltage from Primary 12 v battery ( check the 12 v battery & replace if more then 14 months old )
C 1256 is for Brake actuator (ABS) if there is any brake job done in near past the system need to be bleeded unlike conventional brake bleed or ABS motor will die
C 1300 is related to ABS malfunction out of 4 atleast one wheel is not engaging at the press of pedal
