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Lennox Error Code 70501: Smart room sensor internal data fault (Heat Pump)

Updated · by Aurora Star Tech Inc.

Lennox error code 70501 on a heat pump means: Smart room sensor internal data fault. It is also called Lennox diagnostic code 70501.

Medium severityHeat Pump

Homeowner? What Lennox code 70501 means for you

Check, then call Your heat pump is reporting: Smart room sensor internal data fault. This is often caused by something simple. Try the safe checks below; if the code returns, book a service call before it turns into a no-heat or no-hot-water emergency.

Safe things you can check yourself

  • Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
  • Check both breakers and the outdoor disconnect box beside the outdoor unit; all should be ON.
  • Look at the air filter. If it is grey and clogged, replace it; a blocked filter causes many shutdowns.
  • In winter, keep snow and ice off and away from the outdoor unit. A short defrost cycle with steam is normal.
  • Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.

Call (647) 657-2977Book a service call

Licensed technicians serving Vaughan, Toronto and the GTA.

What does Lennox error code 70501 mean?

Room sensor cannot collect samples or readings out of range, or occupancy sensor voltage below 0.2 V or above 2.5 V. S30/S40 thermostat alert code 70501.

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

Common causes of Lennox code 70501

  • Sensor fault
Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.

Lennox models that use code 70501

EL16KP1-018EL16KP1-024EL16KP1-030EL16KP1-036EL16KP1-042EL16KP1-048EL16KP1-060ML14KP1-018ML14KP1-024ML14KP1-030ML14KP1-036ML14KP1-042ML14KP1-048ML14KP1-060

Other Lennox Heat Pump codes

CodeMeaning
65544More than 8 thermostats in a group
65545Cooling capacity alert
70001IAQ internal sensor fault
70002IAQ internal data fault
70003IAQ side switch in OFF position
70004Replace Smart IAQ monitor
70502Smart room sensor internal fault
70503Smart room sensor low battery
70504Smart room sensor battery 1%
71001Wireless extender internal data fault
71504Suction temperature sensor incorrect reading
71505Liquid temperature sensor incorrect reading

All Lennox Heat Pump error codes →

Lennox code 70501: homeowner questions

What does Lennox code 70501 mean?

Smart room sensor internal data fault. Room sensor cannot collect samples or readings out of range, or occupancy sensor voltage below 0.2 V or above 2.5 V. S30/S40 thermostat alert code 70501.

Is it safe to keep using my heat pump with code 70501?

It depends on the cause. This is often caused by something simple. Try the safe checks below; if the code returns, book a service call before it turns into a no-heat or no-hot-water emergency.

Can I reset Lennox code 70501 myself?

You can try one reset (power off for 30 seconds, then on). If Lennox code 70501 comes back, the cause is still there and a licensed technician should check it.

Who can fix Lennox code 70501 near me?

Aurora Star Tech Inc. repairs Lennox heat pumps in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.

Homeowner help: AC Running But Not Cooling: What to Check · Heat Pump Not Heating or Blowing Cold Air

Troubleshooting guides

Source: Lennox Residential Communicating Systems Alert Code Guide (V2) 100017 (3/2023), Table 2 Alert Codes and Troubleshooting, p.49. Written in our own words as a summary; always check the original manual.

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.

Emergency HVAC Service

647-657-2977