Every day or so after the thermostat stop calling for heat the furnace combustion shuts down but the blower which should time out stays on and it sets a system lockout code 2. Reset restores operation for sometime days or maybe only a few cycles. John Binns e-mail [email protected]

Try checking your air filter and make sure all your vents are open. I was having the same problem with my Rheem unit. If there is not enough air flow it will back flow into the furnace which will cause the system to lockout.