Cause of error code A09

Internal software err ram error

- Internal Software Error.

Solution for error code A09

If persistent locking errors, A09 occur, systematically disconnect all wires that were not supplied by the factory with the exception of the power supply (CH T?stat, DHW T?stat, LWCO and Pumps). If the error code goes away, determine if there may be feedback from one of the circuits. If the Error occurs with all of these disconnected, there is likely a problem with the control board.