Lennox Furnace Error Code E264

E264 is a soft lockout code indicating the furnace exceeded its maximum number of ignition recycles, with the final attempt failing because a limit circuit switch opened or remained open for more than three minutes. The limit circuit includes high-limit and rollout switches that protect the furnace from overheating. The furnace will not resume normal operation until the underlying thermal fault is corrected. Diagnosing this code starts with reviewing the conditions associated with E250, which tracks the individual limit trips that led to the lockout.

The furnace has placed itself in a soft lockout precisely because a safety threshold was crossed multiple times, so continued operation without diagnosis is not advisable. Persistent limit trips can indicate conditions such as severe overheating or, in more serious cases, a cracked heat exchanger that poses a carbon monoxide risk. It is best to leave the furnace off and have a technician inspect it before resuming use.

Repair costs vary widely depending on the root cause. Replacing an air filter is a low-cost fix, typically under $30. A high-limit switch replacement generally runs between $150 and $350 including labor. Blower motor replacement can range from $300 to $700 or more depending on the motor type. If a cracked heat exchanger is found, costs can be significantly higher, sometimes making furnace replacement a more practical option.

A reset may temporarily clear the lockout and allow the furnace to attempt operation again, but the code will return if the root cause has not been fixed. Because E264 occurs after multiple failed recycle attempts, a simple reset is not a repair. Repeated resets without addressing the underlying cause can stress the heat exchanger and other components, potentially leading to more serious damage.

Start by checking the air filter and replacing it if it is dirty, then confirm that all supply and return vents in the home are open and unobstructed. If airflow is not the issue, a technician should test the blower motor, inspect the limit switches for failure, and examine the heat exchanger for cracks or damage. The diagnostic process should follow the steps associated with E250 to identify which specific component in the limit circuit is causing repeated trips.