HVAC Code Lookup

Lennox Furnace Code E250

Soft lockout

The limit switch circuit is open, meaning the furnace overheated. If the limit does not close within three minutes the unit goes into a one hour soft lockout.

Manual wording: “Limit switch circuit open. Check for proper firing rate on furnace. Ensure there is no blockage in heater. Check for proper air flow. If limit not closed within 3 minutes, unit will go into 1-hour soft lockout.”

Documented for: EL296UHE and SLP98UHV series

Likely causes, most common first

  1. Dirty air filter restricting airflow across the heat exchanger
  2. Closed, blocked or undersized supply and return registers
  3. Blower not moving enough air
  4. Furnace overfired, or blockage inside the heater

What you can safely check yourself

  • Check the air filter and replace it if it is dirty
  • Make sure supply and return registers throughout the house are open and not blocked by furniture or rugs
  • Check that the return grille is clear
  • After the furnace has cooled, turn the power switch off for 30 seconds and back on once

When to call a technician

The manual's action is to check firing rate, look for blockage and verify proper air flow. If the code comes back after a clean filter and open vents, have a technician measure temperature rise and airflow. Never jumper or bypass a limit switch.

A Lennox furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Other Lennox codes