Lennox Furnace Error Code 2 Flashes (RAM)

The 2 Flashes (RAM) code means the furnace control board locked out because it could not sense or sustain a flame during the ignition sequence. The board monitors a flame sensor after opening the gas valve and attempting ignition, and if it does not receive a valid flame signal within the trial period, it shuts down and flashes this fault code. The lockout is a safety feature that prevents unburned gas from accumulating in the heat exchanger or flue. Common causes include a dirty flame sensor, a faulty spark electrode, or a gas supply issue.

The lockout itself is a safety response designed to protect your home by stopping the ignition cycle before unburned gas can accumulate. Once the furnace is locked out, it will not continue to try to ignite, which limits the immediate hazard. You should still have the furnace inspected promptly, particularly if you smell gas near the unit, in which case you should leave the home and contact your gas utility before calling for service.

Repair costs depend on which component has failed. Flame sensor cleaning is often a low-cost service call item, while a replacement flame sensor or spark electrode typically adds a modest parts cost on top of labor. A replacement gas valve is a more significant repair, generally running in the range of several hundred dollars including parts and labor. A new control board can range from moderate to high cost depending on the specific model, and if the furnace is older, the technician may recommend weighing repair costs against replacement.

A knowledgeable homeowner can perform some basic checks, such as confirming the gas shutoff valve is fully open and carefully cleaning the flame sensor rod with fine steel wool if they can safely access it. However, testing the spark electrode, gas valve, and control board involves working with high voltage and gas components, so those steps are best left to a licensed HVAC technician. Attempting repairs on gas components without proper training can create safety hazards.

Resetting the furnace by cycling the power or pressing the reset button will clear the lockout and allow the furnace to attempt ignition again. However, if the underlying problem with the flame sensor, spark electrode, gas valve, or burners has not been corrected, the furnace will fail the ignition sequence again and return to lockout. A reset is useful for confirming whether the fault was a one-time anomaly, but repeated lockouts mean the root cause needs to be diagnosed and repaired.