shop engine code came up po477 but cant find anything on utube. HELP IF U CAN

P0477 OBD-II Diagnostic Powertrain (P) Trouble Code Description P0477 OBD-II Trouble Code Exhaust Back Pressure Regulator - Is a variable position valve that controls exhaust back pressure during cold ambient temperatures to increase cab heat and decrease the amount of time needed to defrost Reason For P0477 Code The reason of P0477 OBD-II Engine Trouble Code is P0477 Exhaust Pressure Control Valve Low.