Sorry, but I forgot to reply. The board in the furnace has been replaced a few weeks ago & everything works like a champ with NO error codes. Thx for the terrific advice. Here's a suggestion maybe you can present to Carrier: rather then have to go to the regional Carrier distributor for Svc Bulletins - dealers should be able to access them (& other info) thru some on-line knowledgebase. This way the tech in the field (or back at the shop) can carry a laptop and search the knowledgebase - much the way Microsoft & other tech companies do it.