Subaru WRX P0406:  EGR Sensor “A” → Circuit High

  P0406 is a generic OBDII Diagnostic code.  It deals with the signal coming from the EGR system.  In this case, it means that the signal coming from the EGR system is higher than the specified range  Since it is a generic code, it has the same meaning for the Subaru WRX as it would … Read more