Johnson Controls
Johnson Controls 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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E01
Thermostat display shows E01 and will not connect to Wi‑Fi or Johnson Controls cloud services.
Wi‑Fi Radio Communication Failure
E02
Thermostat displays E02 and cannot detect indoor temperature; screen may show dashes instead of a temperature reading.
Internal Temperature Sensor Failure
E03
E03 displayed and thermostat cannot read remote indoor sensor; remote room temperature not available.
Remote Indoor Sensor Circuit Open/Short
E04
Thermostat shows E04 and will not control humidity; indoor humidity reading may be missing or incorrect.
Internal Humidity Sensor Failure
E05
E05 displayed and thermostat cannot detect outdoor temperature; outdoor temp shows as dashes or N/A.
Outdoor Temperature Sensor Circuit Fault
E06
Thermostat shows E06 and will not energize heating outputs; heat calls may be ignored.
Heating Output Relay Failure
E07
E07 displayed and thermostat will not energize cooling outputs; AC does not start even though cooling is requested.
Cooling Output Relay Failure
E08
Thermostat shows E08 and backlight or display intermittently shuts off; device may reboot randomly.
Low Voltage / Power Supply Fault
E09
E09 displayed and thermostat cannot detect occupancy; smart setback or presence features disabled.
Occupancy / PIR Sensor Failure
E10
Thermostat shows E10 and cannot communicate with Johnson Controls zoning panel or rooftop unit controller over the communication bus.
Communication Bus Failure (BACnet/Modbus/Proprietary)
E11
E11 displayed and thermostat reports internal memory or configuration error; settings may not save.
Non‑Volatile Memory / Configuration Corruption
E12
Thermostat shows E12 and touchscreen does not respond or responds erratically.
Touchscreen Interface Failure
E13
E13 displayed and thermostat indicates fan control fault; fan may run continuously or not at all.
Fan Output Relay or G Circuit Fault
E14
Thermostat shows E14 and indicates dehumidification control fault; dehumidifier or over‑cooling function not working.
Dehumidification Output Fault
E15
E15 displayed and thermostat reports sensor calibration error; temperature or humidity readings appear obviously wrong.
Sensor Calibration Out of Range
E16
Thermostat shows E16 and indicates backup battery or supercapacitor fault; time and settings may reset after power loss.
Real‑Time Clock Backup Power Failure
E17
E17 displayed and thermostat indicates internal over‑temperature; device may shut down or dim the display.
Thermostat Internal Overheat Protection
E18
Thermostat shows E18 and cannot detect or control an external ventilation device (ERV/HRV or fresh air damper).
Ventilation Output or Feedback Fault
E19
E19 displayed and thermostat cannot connect to Johnson Controls cloud or mobile app despite Wi‑Fi being connected.
Cloud Service / API Communication Error
E20
Thermostat shows E20 and indicates C‑wire or power stealing configuration error; device may reboot when HVAC starts.
Common Wire / Power Stealing Configuration Fault
Symptom
Room temperature overshoots the setpoint by several degrees before the system turns off.
Thermostat Anticipation / Cycle Rate Misconfiguration
Symptom
Thermostat and HVAC system run, but indoor humidity remains high and does not reach the setpoint.
Ineffective Dehumidification Control
Symptom
Thermostat backlight flickers or brightness changes unexpectedly while in use.
Display Backlight Power Instability
Symptom
Thermostat calls for cooling, but only the indoor blower runs; outdoor unit does not start.
Cooling Call Not Reaching Condensing Unit
Symptom
Thermostat calls for heat, but only the fan runs and no warm air is produced.
Heat Call Not Reaching Burner/Heat Source
Symptom
Thermostat display is completely blank and unresponsive; HVAC system does not respond to temperature changes.
No Power to Thermostat
Symptom
Thermostat displays temperature that is clearly inaccurate compared to other thermometers in the home.
Temperature Sensing / Placement Error
Symptom
Thermostat does not energize auxiliary or emergency heat on a heat pump system when outdoor temperature is very low.
Aux/E Heat Control Failure
Symptom
Thermostat does not follow programmed schedule; remains at one temperature or changes at wrong times.
Scheduling / Real‑Time Clock Issue
Symptom
Thermostat emits a buzzing or clicking noise when switching modes or calling for heat/cool.
Relay Chatter / Coil Noise
Symptom
Thermostat fails to detect or use a Johnson Controls remote room sensor even though it is wired correctly.
Remote Sensor Detection / Configuration Issue
Symptom
Thermostat frequently reboots or restarts, especially when heating or cooling equipment turns on.
Voltage Drop / Power Instability at Thermostat
Symptom
Thermostat indicates fan is set to ON, but the indoor blower does not run.
Fan Control Circuit Failure
Symptom
Thermostat is powered but HVAC system will not turn on in either heating or cooling mode.
Control Signal Not Reaching HVAC Equipment
Symptom
Thermostat is unresponsive to touch or button presses, but the display is lit and shows current temperature.
User Interface Input Failure
Symptom
Thermostat loses Wi‑Fi settings and must be re‑joined to the network after every power outage.
Non‑Volatile Network Configuration Loss
Symptom
Thermostat plastic housing feels unusually warm to the touch during normal operation.
Excessive Internal Heat Generation
Symptom
Thermostat randomly drops connection to Johnson Controls zoning panel; some zones do not respond.
Intermittent Zoning Communication / Power Issue
Symptom
Thermostat short cycles the HVAC system, turning it on and off frequently within a few minutes.
Excessive Cycling / Differential Too Tight
Symptom
Thermostat shows Wi‑Fi connected but cannot be controlled from the Johnson Controls mobile app intermittently.
Intermittent Network / App Connectivity Issue
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E01 |
Thermostat display shows E01 and will not connect to Wi‑Fi or Johnson Controls cloud services.
|
Wi‑Fi Radio Communication Failure | View Details |
| E02 |
Thermostat displays E02 and cannot detect indoor temperature; screen may show dashes instead of a temperature reading.
|
Internal Temperature Sensor Failure | View Details |
| E03 |
E03 displayed and thermostat cannot read remote indoor sensor; remote room temperature not available.
|
Remote Indoor Sensor Circuit Open/Short | View Details |
| E04 |
Thermostat shows E04 and will not control humidity; indoor humidity reading may be missing or incorrect.
|
Internal Humidity Sensor Failure | View Details |
| E05 |
E05 displayed and thermostat cannot detect outdoor temperature; outdoor temp shows as dashes or N/A.
|
Outdoor Temperature Sensor Circuit Fault | View Details |
| E06 |
Thermostat shows E06 and will not energize heating outputs; heat calls may be ignored.
|
Heating Output Relay Failure | View Details |
| E07 |
E07 displayed and thermostat will not energize cooling outputs; AC does not start even though cooling is requested.
|
Cooling Output Relay Failure | View Details |
| E08 |
Thermostat shows E08 and backlight or display intermittently shuts off; device may reboot randomly.
|
Low Voltage / Power Supply Fault | View Details |
| E09 |
E09 displayed and thermostat cannot detect occupancy; smart setback or presence features disabled.
|
Occupancy / PIR Sensor Failure | View Details |
| E10 |
Thermostat shows E10 and cannot communicate with Johnson Controls zoning panel or rooftop unit controller over the communication bus.
|
Communication Bus Failure (BACnet/Modbus/Proprietary) | View Details |
| E11 |
E11 displayed and thermostat reports internal memory or configuration error; settings may not save.
|
Non‑Volatile Memory / Configuration Corruption | View Details |
| E12 |
Thermostat shows E12 and touchscreen does not respond or responds erratically.
|
Touchscreen Interface Failure | View Details |
| E13 |
E13 displayed and thermostat indicates fan control fault; fan may run continuously or not at all.
|
Fan Output Relay or G Circuit Fault | View Details |
| E14 |
Thermostat shows E14 and indicates dehumidification control fault; dehumidifier or over‑cooling function not working.
|
Dehumidification Output Fault | View Details |
| E15 |
E15 displayed and thermostat reports sensor calibration error; temperature or humidity readings appear obviously wrong.
|
Sensor Calibration Out of Range | View Details |
| E16 |
Thermostat shows E16 and indicates backup battery or supercapacitor fault; time and settings may reset after power loss.
|
Real‑Time Clock Backup Power Failure | View Details |
| E17 |
E17 displayed and thermostat indicates internal over‑temperature; device may shut down or dim the display.
|
Thermostat Internal Overheat Protection | View Details |
| E18 |
Thermostat shows E18 and cannot detect or control an external ventilation device (ERV/HRV or fresh air damper).
|
Ventilation Output or Feedback Fault | View Details |
| E19 |
E19 displayed and thermostat cannot connect to Johnson Controls cloud or mobile app despite Wi‑Fi being connected.
|
Cloud Service / API Communication Error | View Details |
| E20 |
Thermostat shows E20 and indicates C‑wire or power stealing configuration error; device may reboot when HVAC starts.
|
Common Wire / Power Stealing Configuration Fault | View Details |
| – |
Room temperature overshoots the setpoint by several degrees before the system turns off.
|
Thermostat Anticipation / Cycle Rate Misconfiguration | View Details |
| – |
Thermostat and HVAC system run, but indoor humidity remains high and does not reach the setpoint.
|
Ineffective Dehumidification Control | View Details |
| – |
Thermostat backlight flickers or brightness changes unexpectedly while in use.
|
Display Backlight Power Instability | View Details |
| – |
Thermostat calls for cooling, but only the indoor blower runs; outdoor unit does not start.
|
Cooling Call Not Reaching Condensing Unit | View Details |
| – |
Thermostat calls for heat, but only the fan runs and no warm air is produced.
|
Heat Call Not Reaching Burner/Heat Source | View Details |
| – |
Thermostat display is completely blank and unresponsive; HVAC system does not respond to temperature changes.
|
No Power to Thermostat | View Details |
| – |
Thermostat displays temperature that is clearly inaccurate compared to other thermometers in the home.
|
Temperature Sensing / Placement Error | View Details |
| – |
Thermostat does not energize auxiliary or emergency heat on a heat pump system when outdoor temperature is very low.
|
Aux/E Heat Control Failure | View Details |
| – |
Thermostat does not follow programmed schedule; remains at one temperature or changes at wrong times.
|
Scheduling / Real‑Time Clock Issue | View Details |
| – |
Thermostat emits a buzzing or clicking noise when switching modes or calling for heat/cool.
|
Relay Chatter / Coil Noise | View Details |
| – |
Thermostat fails to detect or use a Johnson Controls remote room sensor even though it is wired correctly.
|
Remote Sensor Detection / Configuration Issue | View Details |
| – |
Thermostat frequently reboots or restarts, especially when heating or cooling equipment turns on.
|
Voltage Drop / Power Instability at Thermostat | View Details |
| – |
Thermostat indicates fan is set to ON, but the indoor blower does not run.
|
Fan Control Circuit Failure | View Details |
| – |
Thermostat is powered but HVAC system will not turn on in either heating or cooling mode.
|
Control Signal Not Reaching HVAC Equipment | View Details |
| – |
Thermostat is unresponsive to touch or button presses, but the display is lit and shows current temperature.
|
User Interface Input Failure | View Details |
| – |
Thermostat loses Wi‑Fi settings and must be re‑joined to the network after every power outage.
|
Non‑Volatile Network Configuration Loss | View Details |
| – |
Thermostat plastic housing feels unusually warm to the touch during normal operation.
|
Excessive Internal Heat Generation | View Details |
| – |
Thermostat randomly drops connection to Johnson Controls zoning panel; some zones do not respond.
|
Intermittent Zoning Communication / Power Issue | View Details |
| – |
Thermostat short cycles the HVAC system, turning it on and off frequently within a few minutes.
|
Excessive Cycling / Differential Too Tight | View Details |
| – |
Thermostat shows Wi‑Fi connected but cannot be controlled from the Johnson Controls mobile app intermittently.
|
Intermittent Network / App Connectivity Issue | View Details |
No matching codes found
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