American Standard Smart Thermostats Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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E0
Thermostat display shows E0 and will not control heating or cooling
Internal Configuration / Firmware Fault
E1
Thermostat displays E1 and system will not run or runs only in emergency mode
Indoor Temperature Sensor Fault
E10
Thermostat shows E10 and cannot complete initial system configuration
System Configuration / Equipment Mismatch Fault
E11
Thermostat displays E11 and remote wireless sensors are not detected
Wireless Remote Sensor Communication Fault
E12
Thermostat shows E12 and schedules or settings are not saving correctly
Non-Volatile Memory / Data Storage Fault
E13
Thermostat displays E13 and cannot connect to American Standard cloud services
Cloud Service / Server Communication Fault
E14
Thermostat shows E14 and geofencing or location-based features do not work
Location Services / GPS Integration Fault
E15
Thermostat displays E15 and fails to control whole-home humidifier
Humidifier Control Circuit Fault
E16
Thermostat shows E16 and dehumidification or overcooling features do not work
Dehumidification Control Fault
E17
Thermostat displays E17 and ventilation or ERV/HRV control is disabled
Ventilation Control Fault
E18
Thermostat shows E18 and fan control is erratic or stuck on/off
Indoor Fan (G Terminal) Control Fault
E19
Thermostat displays E19 and heat pump reversing valve does not operate correctly
Reversing Valve (O/B) Control Fault
E2
Thermostat shows E2 and may default to backup temperature or shut down heating/cooling
Remote Indoor Sensor Fault
E3
Thermostat displays E3 and outdoor temperature reading is missing or incorrect
Outdoor Temperature Sensor Fault
E4
Thermostat shows E4 and may not control humidity or dehumidification properly
Indoor Humidity Sensor Fault
E5
Thermostat displays E5 and Wi‑Fi or cloud features are unavailable
Wi‑Fi Module / Network Communication Fault
E6
Thermostat shows E6 and cannot communicate with the American Standard communicating HVAC system
Communicating Bus Fault (AUX/ABC or Data Bus)
E7
Thermostat displays E7 and system may lock out heating or cooling
High/Low Voltage Supply Fault to Thermostat
E8
Thermostat shows E8 and cooling or heating stages do not respond correctly
Output Relay / Stage Control Fault
E9
Thermostat displays E9 and may reboot repeatedly or freeze
Overtemperature / Internal Overheat Protection
Symptom
Thermostat backlight is very dim or flickers, but unit otherwise works
Display Backlight Power Issue
Symptom
Thermostat calls for cooling but outdoor unit does not run; indoor blower may run
Outdoor Unit Not Responding to Cooling Call
Symptom
Thermostat calls for heat but furnace does not start; display shows normal operation, no code
Open Heat Call Circuit or Furnace Control Board Issue
Symptom
Thermostat cycles heating or cooling on and off very frequently (short cycling)
Improper Cycle Rate / Differential Settings or Sensing Location Issue
Symptom
Thermostat display is completely blank and system does not run
Loss of 24V Power to Thermostat
Symptom
Thermostat does not follow programmed schedule; temperature changes at unexpected times
Scheduling / Timekeeping Issue
Symptom
Thermostat does not power up after replacement or new installation
Incorrect Wiring / Missing Common (C) Wire
Symptom
Thermostat fails to control whole-home humidifier even though humidity readings are normal
Humidifier Integration / Control Logic Issue
Symptom
Thermostat fails to dehumidify using AC overcooling; humidity remains high
Dehumidification via Overcooling Not Operating
Symptom
Thermostat frequently reboots or freezes, even with no error code
Unstable Power or Internal Electronics Fault
Symptom
Thermostat humidity reading is clearly wrong or stuck at 0%/100%
Indoor Humidity Sensing Issue
Symptom
Thermostat is on but does not call for cooling when room is warm
Cooling Call Not Initiated or Not Recognized
Symptom
Thermostat is on but does not call for heat when room is cold
Heating Call Not Initiated or Not Recognized
Symptom
Thermostat loses date/time after power outages and does not resync automatically
Timekeeping / NTP Sync Failure
Symptom
Thermostat shows connected in app but remote commands are delayed or not executed
Cloud Command Latency / Sync Issue
Symptom
Thermostat temperature reading is inaccurate compared to actual room temperature
Room Temperature Sensing / Calibration Issue
Symptom
Thermostat touchscreen is unresponsive or only responds intermittently
Touchscreen / User Interface Failure
Symptom
Thermostat Wi‑Fi connection drops frequently or app cannot reliably control the thermostat
Intermittent Wi‑Fi Connectivity
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E0 |
Thermostat display shows E0 and will not control heating or cooling
|
Internal Configuration / Firmware Fault | View Details |
| E1 |
Thermostat displays E1 and system will not run or runs only in emergency mode
|
Indoor Temperature Sensor Fault | View Details |
| E10 |
Thermostat shows E10 and cannot complete initial system configuration
|
System Configuration / Equipment Mismatch Fault | View Details |
| E11 |
Thermostat displays E11 and remote wireless sensors are not detected
|
Wireless Remote Sensor Communication Fault | View Details |
| E12 |
Thermostat shows E12 and schedules or settings are not saving correctly
|
Non-Volatile Memory / Data Storage Fault | View Details |
| E13 |
Thermostat displays E13 and cannot connect to American Standard cloud services
|
Cloud Service / Server Communication Fault | View Details |
| E14 |
Thermostat shows E14 and geofencing or location-based features do not work
|
Location Services / GPS Integration Fault | View Details |
| E15 |
Thermostat displays E15 and fails to control whole-home humidifier
|
Humidifier Control Circuit Fault | View Details |
| E16 |
Thermostat shows E16 and dehumidification or overcooling features do not work
|
Dehumidification Control Fault | View Details |
| E17 |
Thermostat displays E17 and ventilation or ERV/HRV control is disabled
|
Ventilation Control Fault | View Details |
| E18 |
Thermostat shows E18 and fan control is erratic or stuck on/off
|
Indoor Fan (G Terminal) Control Fault | View Details |
| E19 |
Thermostat displays E19 and heat pump reversing valve does not operate correctly
|
Reversing Valve (O/B) Control Fault | View Details |
| E2 |
Thermostat shows E2 and may default to backup temperature or shut down heating/cooling
|
Remote Indoor Sensor Fault | View Details |
| E3 |
Thermostat displays E3 and outdoor temperature reading is missing or incorrect
|
Outdoor Temperature Sensor Fault | View Details |
| E4 |
Thermostat shows E4 and may not control humidity or dehumidification properly
|
Indoor Humidity Sensor Fault | View Details |
| E5 |
Thermostat displays E5 and Wi‑Fi or cloud features are unavailable
|
Wi‑Fi Module / Network Communication Fault | View Details |
| E6 |
Thermostat shows E6 and cannot communicate with the American Standard communicating HVAC system
|
Communicating Bus Fault (AUX/ABC or Data Bus) | View Details |
| E7 |
Thermostat displays E7 and system may lock out heating or cooling
|
High/Low Voltage Supply Fault to Thermostat | View Details |
| E8 |
Thermostat shows E8 and cooling or heating stages do not respond correctly
|
Output Relay / Stage Control Fault | View Details |
| E9 |
Thermostat displays E9 and may reboot repeatedly or freeze
|
Overtemperature / Internal Overheat Protection | View Details |
| – |
Thermostat backlight is very dim or flickers, but unit otherwise works
|
Display Backlight Power Issue | View Details |
| – |
Thermostat calls for cooling but outdoor unit does not run; indoor blower may run
|
Outdoor Unit Not Responding to Cooling Call | View Details |
| – |
Thermostat calls for heat but furnace does not start; display shows normal operation, no code
|
Open Heat Call Circuit or Furnace Control Board Issue | View Details |
| – |
Thermostat cycles heating or cooling on and off very frequently (short cycling)
|
Improper Cycle Rate / Differential Settings or Sensing Location Issue | View Details |
| – |
Thermostat display is completely blank and system does not run
|
Loss of 24V Power to Thermostat | View Details |
| – |
Thermostat does not follow programmed schedule; temperature changes at unexpected times
|
Scheduling / Timekeeping Issue | View Details |
| – |
Thermostat does not power up after replacement or new installation
|
Incorrect Wiring / Missing Common (C) Wire | View Details |
| – |
Thermostat fails to control whole-home humidifier even though humidity readings are normal
|
Humidifier Integration / Control Logic Issue | View Details |
| – |
Thermostat fails to dehumidify using AC overcooling; humidity remains high
|
Dehumidification via Overcooling Not Operating | View Details |
| – |
Thermostat frequently reboots or freezes, even with no error code
|
Unstable Power or Internal Electronics Fault | View Details |
| – |
Thermostat humidity reading is clearly wrong or stuck at 0%/100%
|
Indoor Humidity Sensing Issue | View Details |
| – |
Thermostat is on but does not call for cooling when room is warm
|
Cooling Call Not Initiated or Not Recognized | View Details |
| – |
Thermostat is on but does not call for heat when room is cold
|
Heating Call Not Initiated or Not Recognized | View Details |
| – |
Thermostat loses date/time after power outages and does not resync automatically
|
Timekeeping / NTP Sync Failure | View Details |
| – |
Thermostat shows connected in app but remote commands are delayed or not executed
|
Cloud Command Latency / Sync Issue | View Details |
| – |
Thermostat temperature reading is inaccurate compared to actual room temperature
|
Room Temperature Sensing / Calibration Issue | View Details |
| – |
Thermostat touchscreen is unresponsive or only responds intermittently
|
Touchscreen / User Interface Failure | View Details |
| – |
Thermostat Wi‑Fi connection drops frequently or app cannot reliably control the thermostat
|
Intermittent Wi‑Fi Connectivity | View Details |
No matching codes found
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