HVACopedia

Lennox · Furnace

70001 IAQ internal sensor fault

Medium severity

What the control is telling you

Smart IAQ monitor CO2, VOC or PM sensor lost internal communication or data out of range. S30/S40 thermostat alert code 70001.

Applies to: Lennox communicating gas furnaces (e.g. SL280UHV/SL280UHNV, EL296UHV) in S30/S40 smart thermostat systems

Likely causes

  • Device internal fault

Test and repair steps

  1. Cycle device power (press pairing button one second).
  2. If not fixed remove from BLE network, factory reset, add back.
  3. Replace device if it persists.

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Source: Lennox Residential Communicating Systems Alert Code Guide (V2) 100017 (3/2023), Table 2 Alert Codes and Troubleshooting, p.48. 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.