Cause of error code A12

Software out of date E2prom out of date.

- Possible version mismatch between control and other components.

Solution for error code A12

- If persistent locking errors, A12 occur, systematically disconnect all wires not supplied by the factory with the exception of the power supply (CH T’Stat, DHW T’Stat, LWCO, Pumps, etc.). If the error code goes away, determine which circuit may be introducing electrical noise or feedback. 
- If the error persists after all these wires are disconnected, contact your PB Heat representative. 
- If this error occurs after replacing a control, contact your PB Heat representative.