HVACopedia

Lennox · Heat pump

E416 Outdoor coil sensor faulty

Medium severity

What the control is telling you

Outdoor coil sensor is open, shorted or out of range (checked after 90 seconds of run). No demand or time/temperature defrost; unit still heats and cools. Moderate becomes critical after 10 minutes. S30/S40 thermostat alert code 416 (shown as E416 on the unit control display).

Applies to: Lennox communicating heat pumps incl. variable-capacity inverter units in S30/S40 smart thermostat systems

Likely causes

  • Sensor harness unplugged
  • Open/shorted sensor

Test and repair steps

  1. Plug the sensor harness in correctly.
  2. Check sensor resistance against the chart; replace if out of spec.
  3. If critical, replace the sensor and reset power.

Settings for these units

Save it for the next call

Star this code in the HVACopedia app and keep the whole library on your phone for jobs with no signal.

Open the app

Source: Lennox Residential Communicating Systems Alert Code Guide (V2) 100017 (3/2023), Table 2 Alert Codes and Troubleshooting, p.31. Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.