Lennox Furnace Error Code Steady ON (RAM)

The Steady ON (RAM) code means the furnace control board has detected a failure in its internal Random Access Memory. This is an internal hardware fault within the control board itself. The board runs self-checks continuously, and when RAM is found to be non-functional, it sets this fault and shuts down normal furnace operation. Board replacement is the required repair.

No, resetting the furnace by cycling power will not resolve a RAM fault. Because the failure is internal to the control board hardware, the board will detect the same RAM error every time it powers up and runs its self-diagnostic routine. The fault will persist until the board is replaced.

The primary cost is the replacement control board, which typically ranges from $150 to $600 or more depending on the specific Lennox model. Adding labor for diagnosis and installation, total repair costs generally fall in the range of $300 to $900. Getting a quote from a licensed HVAC technician for your specific furnace model is the best way to get an accurate estimate.

The RAM fault points directly to a failed control board, and the board is not a user-serviceable component. Replacing a furnace control board involves working with line voltage wiring and precise connector reassembly, which is best handled by a licensed HVAC technician. There are no field-level repairs to the RAM itself since the chips are soldered onto the board.

When this fault is active, the furnace control board is not operating correctly and the furnace will not run through its normal heating cycle. You should not attempt to force the furnace to operate. Leave the furnace off and contact a qualified technician to diagnose and replace the control board.