Rheem 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 communicate with the HVAC equipment or mobile app.
Communication Bus Failure
E1
Thermostat displays E1 and will not control heating or cooling; may show 'Indoor sensor error'.
Indoor Temperature Sensor Failure
E10
Thermostat shows E10 and may indicate 'Overheat protection' or 'Thermostat temperature too high'; screen may dim or shut down.
Thermostat Over-Temperature Protection
E11
Thermostat displays E11 and may indicate 'Dehumidifier control error' or 'Dehum output fault'.
Dehumidification Control Circuit Fault
E12
Thermostat shows E12 and may indicate 'Aux heat lockout' or 'Auxiliary heat control error' on heat pump systems.
Auxiliary Heat Control Fault
E13
Thermostat displays E13 and may indicate 'Fan control error' or 'G output fault'; blower does not respond correctly.
Indoor Blower Fan Control Fault from Thermostat
E14
Thermostat shows E14 and may indicate 'Reversing valve control error' on heat pump systems.
Reversing Valve (O/B) Control Fault
E15
Thermostat displays E15 and may indicate 'Compressor lockout active' or 'High/low pressure lockout'.
Compressor Safety Lockout Indication
E16
Thermostat shows E16 and may indicate 'Defrost control error' on heat pump systems.
Defrost Control Communication Fault
E17
Thermostat displays E17 and may indicate 'Emergency heat error' or 'E-heat control fault' on dual-fuel or heat pump systems.
Emergency Heat Control Fault
E18
Thermostat shows E18 and may indicate 'Sensor calibration error' or 'Temperature/humidity out of range'.
Sensor Calibration / Range Fault
E19
Thermostat displays E19 and may indicate 'Schedule memory error' or 'Timekeeping fault'; schedules may not run correctly.
Real-Time Clock / Schedule Memory Fault
E2
Thermostat shows E2 and may indicate 'Outdoor sensor error' or 'Outdoor temp unavailable'.
Outdoor Temperature Sensor Circuit Fault
E20
Thermostat shows E20 and may indicate 'Zoning communication error' on systems with Rheem zoning panels.
Zone Panel Communication Fault
E3
Thermostat displays E3 and may show 'Humidity sensor error' or inaccurate indoor humidity readings.
Indoor Humidity Sensor Failure
E4
Thermostat shows E4 and may indicate 'Low voltage' or '24V power error'; display may dim or reboot.
Low Voltage Power Supply Fault
E5
Thermostat displays E5 and may indicate 'High voltage' or 'Power surge detected'; system may lock out temporarily.
High Voltage or Power Surge Detection
E6
Thermostat shows E6 and may indicate 'Wi-Fi module error' or 'Network hardware fault'; cannot connect to app.
Wi-Fi Communication Module Failure
E7
Thermostat displays E7 and may indicate 'Equipment communication error' or 'No response from indoor unit'.
Indoor Unit Communication Loss
E8
Thermostat shows E8 and may indicate 'Outdoor unit communication error' or 'No response from condenser/heat pump'.
Outdoor Unit Communication Loss
E9
Thermostat displays E9 and may indicate 'Internal memory error' or 'Configuration fault'; settings may reset unexpectedly.
Non-Volatile Memory / Configuration Corruption
Symptom
Thermostat backlight is very dim or flickers intermittently.
Display Backlight Power Issue
Symptom
Thermostat calls for cooling but the air conditioner does not start; indoor blower may run.
No Cooling Call Reaching Outdoor Unit
Symptom
Thermostat calls for heat but the furnace or heat pump does not start; fan may or may not run.
No Heating Call Reaching Equipment
Symptom
Thermostat clicks or relays chatter repeatedly without the HVAC equipment starting properly.
Unstable Control Signal or Relay Chatter
Symptom
Thermostat display is completely blank and unresponsive; HVAC system does not run.
No Power to Thermostat
Symptom
Thermostat does not follow programmed schedule; temperature holds at one setting.
Scheduling / Hold Mode Misconfiguration
Symptom
Thermostat does not respond to touch or buttons, but the display is lit.
Unresponsive User Interface / Touchscreen Failure
Symptom
Thermostat emits a burning smell or feels unusually hot to the touch.
Overheating or Electrical Damage in Thermostat
Symptom
Thermostat frequently cycles the HVAC system on and off in short intervals (short cycling).
Improper Cycle Rate / Differential Settings or Equipment Protection
Symptom
Thermostat frequently disconnects from Wi-Fi or shows poor signal strength.
Unstable Wi-Fi Connection
Symptom
Thermostat is not controlling a whole-house dehumidifier or overcooling for dehumidification as expected.
Dehumidification Control Not Operating
Symptom
Thermostat is not controlling a whole-house humidifier connected to it; humidity does not increase when expected.
Humidifier Control Output Failure
Symptom
Thermostat loses date/time and settings after a power outage.
Loss of Non-Volatile Settings or Clock Backup
Symptom
Thermostat powers on but frequently reboots or restarts by itself.
Unstable Thermostat Power or Internal Fault
Symptom
Thermostat randomly changes setpoints or mode without user input.
Unexpected Control Changes (Scheduling or Remote Control)
Symptom
Thermostat shows incorrect room temperature compared to other thermometers in the home.
Temperature Sensing / Calibration Issue
Symptom
Thermostat shows very high or very low indoor humidity readings that do not match other hygrometers.
Humidity Sensing / Calibration Issue
Symptom
Thermostat shows Wi-Fi connected but does not appear in the Rheem app or cannot be controlled remotely.
Cloud Connectivity / Account Linking Issue
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E0 |
Thermostat display shows E0 and will not communicate with the HVAC equipment or mobile app.
|
Communication Bus Failure | View Details |
| E1 |
Thermostat displays E1 and will not control heating or cooling; may show 'Indoor sensor error'.
|
Indoor Temperature Sensor Failure | View Details |
| E10 |
Thermostat shows E10 and may indicate 'Overheat protection' or 'Thermostat temperature too high'; screen may dim or shut down.
|
Thermostat Over-Temperature Protection | View Details |
| E11 |
Thermostat displays E11 and may indicate 'Dehumidifier control error' or 'Dehum output fault'.
|
Dehumidification Control Circuit Fault | View Details |
| E12 |
Thermostat shows E12 and may indicate 'Aux heat lockout' or 'Auxiliary heat control error' on heat pump systems.
|
Auxiliary Heat Control Fault | View Details |
| E13 |
Thermostat displays E13 and may indicate 'Fan control error' or 'G output fault'; blower does not respond correctly.
|
Indoor Blower Fan Control Fault from Thermostat | View Details |
| E14 |
Thermostat shows E14 and may indicate 'Reversing valve control error' on heat pump systems.
|
Reversing Valve (O/B) Control Fault | View Details |
| E15 |
Thermostat displays E15 and may indicate 'Compressor lockout active' or 'High/low pressure lockout'.
|
Compressor Safety Lockout Indication | View Details |
| E16 |
Thermostat shows E16 and may indicate 'Defrost control error' on heat pump systems.
|
Defrost Control Communication Fault | View Details |
| E17 |
Thermostat displays E17 and may indicate 'Emergency heat error' or 'E-heat control fault' on dual-fuel or heat pump systems.
|
Emergency Heat Control Fault | View Details |
| E18 |
Thermostat shows E18 and may indicate 'Sensor calibration error' or 'Temperature/humidity out of range'.
|
Sensor Calibration / Range Fault | View Details |
| E19 |
Thermostat displays E19 and may indicate 'Schedule memory error' or 'Timekeeping fault'; schedules may not run correctly.
|
Real-Time Clock / Schedule Memory Fault | View Details |
| E2 |
Thermostat shows E2 and may indicate 'Outdoor sensor error' or 'Outdoor temp unavailable'.
|
Outdoor Temperature Sensor Circuit Fault | View Details |
| E20 |
Thermostat shows E20 and may indicate 'Zoning communication error' on systems with Rheem zoning panels.
|
Zone Panel Communication Fault | View Details |
| E3 |
Thermostat displays E3 and may show 'Humidity sensor error' or inaccurate indoor humidity readings.
|
Indoor Humidity Sensor Failure | View Details |
| E4 |
Thermostat shows E4 and may indicate 'Low voltage' or '24V power error'; display may dim or reboot.
|
Low Voltage Power Supply Fault | View Details |
| E5 |
Thermostat displays E5 and may indicate 'High voltage' or 'Power surge detected'; system may lock out temporarily.
|
High Voltage or Power Surge Detection | View Details |
| E6 |
Thermostat shows E6 and may indicate 'Wi-Fi module error' or 'Network hardware fault'; cannot connect to app.
|
Wi-Fi Communication Module Failure | View Details |
| E7 |
Thermostat displays E7 and may indicate 'Equipment communication error' or 'No response from indoor unit'.
|
Indoor Unit Communication Loss | View Details |
| E8 |
Thermostat shows E8 and may indicate 'Outdoor unit communication error' or 'No response from condenser/heat pump'.
|
Outdoor Unit Communication Loss | View Details |
| E9 |
Thermostat displays E9 and may indicate 'Internal memory error' or 'Configuration fault'; settings may reset unexpectedly.
|
Non-Volatile Memory / Configuration Corruption | View Details |
| – |
Thermostat backlight is very dim or flickers intermittently.
|
Display Backlight Power Issue | View Details |
| – |
Thermostat calls for cooling but the air conditioner does not start; indoor blower may run.
|
No Cooling Call Reaching Outdoor Unit | View Details |
| – |
Thermostat calls for heat but the furnace or heat pump does not start; fan may or may not run.
|
No Heating Call Reaching Equipment | View Details |
| – |
Thermostat clicks or relays chatter repeatedly without the HVAC equipment starting properly.
|
Unstable Control Signal or Relay Chatter | View Details |
| – |
Thermostat display is completely blank and unresponsive; HVAC system does not run.
|
No Power to Thermostat | View Details |
| – |
Thermostat does not follow programmed schedule; temperature holds at one setting.
|
Scheduling / Hold Mode Misconfiguration | View Details |
| – |
Thermostat does not respond to touch or buttons, but the display is lit.
|
Unresponsive User Interface / Touchscreen Failure | View Details |
| – |
Thermostat emits a burning smell or feels unusually hot to the touch.
|
Overheating or Electrical Damage in Thermostat | View Details |
| – |
Thermostat frequently cycles the HVAC system on and off in short intervals (short cycling).
|
Improper Cycle Rate / Differential Settings or Equipment Protection | View Details |
| – |
Thermostat frequently disconnects from Wi-Fi or shows poor signal strength.
|
Unstable Wi-Fi Connection | View Details |
| – |
Thermostat is not controlling a whole-house dehumidifier or overcooling for dehumidification as expected.
|
Dehumidification Control Not Operating | View Details |
| – |
Thermostat is not controlling a whole-house humidifier connected to it; humidity does not increase when expected.
|
Humidifier Control Output Failure | View Details |
| – |
Thermostat loses date/time and settings after a power outage.
|
Loss of Non-Volatile Settings or Clock Backup | View Details |
| – |
Thermostat powers on but frequently reboots or restarts by itself.
|
Unstable Thermostat Power or Internal Fault | View Details |
| – |
Thermostat randomly changes setpoints or mode without user input.
|
Unexpected Control Changes (Scheduling or Remote Control) | View Details |
| – |
Thermostat shows incorrect room temperature compared to other thermometers in the home.
|
Temperature Sensing / Calibration Issue | View Details |
| – |
Thermostat shows very high or very low indoor humidity readings that do not match other hygrometers.
|
Humidity Sensing / Calibration Issue | View Details |
| – |
Thermostat shows Wi-Fi connected but does not appear in the Rheem app or cannot be controlled remotely.
|
Cloud Connectivity / Account Linking Issue | View Details |
No matching codes found
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