Lennox HVAC Error Code 206

Error code 206 on a Lennox air handler indicates a problem with the discharge air sensor, which is the component that measures the temperature of air leaving the air handler and entering the ductwork. The control board has detected that the sensor's signal is outside the acceptable range. This can be caused by a failed sensor, loose wiring, or corroded connector pins. The fault clears automatically 30 seconds after the sensor signal returns to a normal reading.

A faulty discharge air sensor means the control board cannot accurately monitor the air temperature leaving your air handler, which can interfere with proper system protection and regulation. Running the system continuously in this condition is not recommended, as the board may not respond correctly to temperature extremes in the duct system. It is best to address the fault promptly to avoid potential secondary issues.

Error code 206 is designed to clear automatically 30 seconds after the control board detects that the sensor signal has recovered to an acceptable range, so a manual reset is not always required. However, if the underlying problem has not been corrected, the fault will return as soon as the system operates again. A power cycle reset may temporarily suppress the code, but it will not fix a failed sensor, damaged wire, or corroded connector. The root cause must be identified and corrected for the fault to stay cleared.

A knowledgeable DIYer can inspect the sensor wiring and connectors for looseness or visible corrosion, which are common causes of this fault. However, confirming sensor failure requires comparing its resistance to a temperature-resistance chart from the installation documentation, which involves using a multimeter correctly. If the sensor needs replacement or the wiring is damaged, comfort with basic electrical work is necessary. When in doubt, a licensed HVAC technician should perform the diagnosis and repair.

If only a connector cleaning or wiring reconnection is needed, the repair cost is primarily a service call fee, which typically ranges from $75 to $150 depending on your area. If the discharge air sensor itself requires replacement, parts and labor combined generally fall in the range of $100 to $300. A control board replacement, which is the least common outcome, would cost significantly more. Getting a diagnostic quote from a licensed technician before authorizing parts replacement is always advisable.