Mastertemp 250 e09 error


New member
Oct 25, 2018
Sarasota Florida
Friends, I am losing my mind here. Had a mastertemp 400, was replacing just about every part on it when the exchanger failed. Bought a 250 in like new condition. Hooked up 250. 250 had no power, bad transformer. Swapped transformer,...power! yay. 250 board blew fuse, continues to blow fuse.

Grabbed board from 400, installed in 250. Power cycles without blowing fuse! Yay. Throws a weird error (flashes 128 then an e09 error I believe)

Tried to bypass board with jumper 5/6 to see if unit would power on. No luck.

The 400 was older and the 250 is less old. Anyone have any ideas here?

All parts are still good on the 400 with the exception of (manifold needs replaced, blower quit working, bad exchanger).

Any troubleshooting ideas? I really don't want to buy a new one as I am now down even more with the used 250 I bought not working.