Lennox EL296UHV Error Code E 180: Outdoor Air Temperature Sensor Failure
What Does Code E 180 Mean?
The Lennox EL296UHV is an icomfort-communicating, two-stage furnace, and its SureLight integrated control uses an outdoor air temperature sensor to inform comfort and staging decisions. When that sensor circuit reads shorted or delivers a value outside the expected temperature range, the control logs E180 and disregards the bad reading.
This is a low-severity fault. The furnace does not shut down for gas-safety reasons the way it does for a rollout or ignition lockout, so warm air normally keeps flowing. What changes is that the control can no longer see an accurate outdoor temperature, which can affect how it manages comfort features and how the icomfort thermostat displays outdoor conditions.
Because E180 is a monitoring fault, the control clears it automatically about 30 seconds after the sensor returns to a valid reading. A code that keeps returning points to a genuinely failed sensor pack or a wiring problem rather than a momentary glitch.
E180 is closely related to E310, the discharge (supply air) temperature sensor fault. Both are temperature-sensing inputs on the same SureLight control, so seeing them together suggests a broader sensor harness or connection issue rather than a single failed sensor.
What You'll Notice
- The seven-segment display shows E 180
- The icomfort thermostat shows a blank, dashed, or clearly wrong outdoor temperature
- The furnace still lights and heats the home more or less normally
- The code disappears and reappears as conditions change, rather than staying constant
- Comfort or staging behavior seems slightly off even though heat is being delivered
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Shorted or out-of-range outdoor temperature sensor | Most common | ✗ Call a pro → |
How This Is Diagnosed
A technician first confirms the reading is truly bad rather than an extreme but real outdoor temperature. They locate the outdoor sensor pack, disconnect it, and measure its resistance, then compare that value against Lennox's temperature/resistance chart for the expected outdoor conditions. A reading of zero ohms (shorted), infinite ohms (open), or one far off the chart confirms a failed sensor.
Before condemning the sensor, the technician inspects the sensor leads and the connector at the control for corrosion, pinched wires, or a loose terminal, since a damaged harness can mimic a shorted sensor. If the resistance is out of range and the wiring checks out, the sensor pack is replaced and the code should self-clear about 30 seconds after a valid reading is restored.
When to Call a Professional
This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:
- The code keeps returning after outdoor temperatures have settled into a normal range
- The icomfort thermostat consistently shows a missing or obviously incorrect outdoor temperature
- E310 (discharge air temperature sensor fault) is also present
- Comfort or staging behavior seems degraded while E180 is displayed
Frequently Asked Questions
Is E180 dangerous or a fire risk?
No. E180 is a low-severity sensor fault, not a combustion or gas-safety condition. The furnace generally keeps heating, but the outdoor temperature reading the control uses is unreliable until the sensor is repaired.
Will my furnace still heat with E180 showing?
In most cases yes. Unlike a rollout or ignition lockout, this fault does not stop the burners, though comfort or staging features that depend on outdoor temperature may not behave as intended.
Why did E180 clear on its own?
The control automatically drops this code roughly 30 seconds after the sensor reads a valid value again. If it clears and returns repeatedly, the sensor or its wiring is likely intermittently failing and should be checked.
✓ Verified against manufacturer service manual — March 2026