Lennox Furnace Error Code E250: How to Fix It

Q: What causes Lennox furnace error code E250?

Error code E250 is caused by a software version mismatch between connected components in your Lennox HVAC system, such as the thermostat, control board, and other communicating accessories having different firmware versions.

Q: Can I fix Lennox error E250 myself?

Yes, you can often fix error E250 yourself by updating the firmware on your thermostat and other connected components. Most modern Lennox systems allow firmware updates through the thermostat interface or mobile app.

Q: How long does it take to update Lennox furnace firmware?

Firmware updates typically take 10-20 minutes per component. The entire process including all components and system restart usually takes 30-60 minutes depending on how many connected devices you have.

Q: Will I lose my thermostat settings after a firmware update?

Most firmware updates preserve your existing settings, but it's good practice to note down your current temperature schedules and preferences before updating, just in case you need to reprogram them.

Q: What if the E250 error persists after firmware updates?

If error E250 continues after updating all components, there may be a hardware communication issue or corrupted firmware that requires professional diagnosis and repair by a certified Lennox technician.

Abstract

Error code E250 on your Lennox furnace indicates a software mismatch between connected components in your HVAC system. This typically occurs when one component has been updated while others remain on older firmware versions, causing communication problems.