Baxi 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 cannot communicate with the boiler; heating does not start.
Boiler Communication Failure
E02
Thermostat shows E02 and will not connect to the internet or Baxi cloud services.
Wi‑Fi Connectivity Failure
E03
Thermostat displays E03 and shows no temperature reading from the room sensor.
Internal Room Temperature Sensor Failure
E04
Thermostat shows E04 and cannot detect the external wired sensor (e.g. remote room or floor sensor).
External Sensor Circuit Open or Short
E05
Thermostat displays E05 and the boiler does not respond to heat demands.
Relay Output Failure
E06
Thermostat shows E06 and cannot pair with the wireless receiver; no RF link.
RF Pairing / Radio Link Failure
E07
Thermostat displays E07 and time/programming resets unexpectedly.
Internal Backup Power / Memory Fault
E08
Thermostat shows E08 and the measured room temperature is clearly incorrect (e.g. 0°C or 99°C).
Temperature Sensor Out of Range
E09
Thermostat displays E09 and cannot control domestic hot water schedule or temperature.
Hot Water Control Channel Failure
E10
Thermostat shows E10 and indicates low supply voltage or power fault.
Low Voltage / Power Supply Error
E11
Thermostat displays E11 and cannot complete firmware update via the Baxi app.
Firmware Update Failure
E12
Thermostat shows E12 and cannot connect to the Baxi cloud or mobile app even though Wi‑Fi is working.
Cloud Service / Server Communication Error
E13
Thermostat displays E13 and schedules or settings cannot be saved.
Non-Volatile Memory Write Error
E14
Thermostat shows E14 and indicates an internal temperature too high; device may shut down.
Thermostat Overtemperature Protection
E15
Thermostat displays E15 and cannot detect the boiler type or configuration.
Auto-Configuration / Boiler Type Detection Error
E16
Thermostat shows E16 and indicates a fault with the humidity sensor (if equipped).
Internal Humidity Sensor Failure
E17
Thermostat displays E17 and cannot read the outdoor temperature from an external sensor or internet source.
Outdoor Temperature Source Failure
E18
Thermostat shows E18 and indicates an internal clock or time sync error.
Real-Time Clock / Time Synchronization Fault
E19
Thermostat displays E19 and indicates an internal sensor self-test failure at startup.
Self-Diagnostic Hardware Failure
E20
Thermostat shows E20 and indicates a zone configuration or multi-zone communication error.
Multi-Zone Control Communication Fault
Symptom
Heating stays on constantly even when thermostat is set low or turned off.
Stuck Heating Relay / Permanent Call for Heat
Symptom
Room temperature overshoots setpoint by several degrees before boiler turns off.
Poor Temperature Control / Overshoot
Symptom
Thermostat appears on but boiler does not fire when heat is requested; no error code on thermostat.
No Heat Demand Reaching Boiler
Symptom
Thermostat batteries drain very quickly (within weeks) on a battery-powered Baxi smart thermostat.
Excessive Battery Consumption
Symptom
Thermostat buttons or touchscreen are unresponsive or respond intermittently.
User Interface / Keypad Failure
Symptom
Thermostat display completely blank; no lights or response.
No Power to Thermostat
Symptom
Thermostat does not follow programmed schedule; heating comes on at wrong times.
Scheduling / Programming Fault
Symptom
Thermostat fails to control underfloor heating correctly; floor gets too hot or too cold.
Incorrect Underfloor Heating Configuration
Symptom
Thermostat frequently loses connection to the receiver; heating cuts in and out unpredictably.
Intermittent RF Communication
Symptom
Thermostat frequently reboots or restarts on its own.
Intermittent Power or Firmware Instability
Symptom
Thermostat or receiver casing is unusually warm to the touch during normal operation.
Mild Overheating / High Load Operation
Symptom
Thermostat or receiver emits a buzzing or humming noise during operation.
Electrical Noise / Coil Vibration
Symptom
Thermostat or receiver has a burnt smell or visible scorch marks.
Overheating / Component Burnout
Symptom
Thermostat shows domestic hot water as ON but hot water does not heat as expected.
Hot Water Demand Not Reaching Boiler or Cylinder
Symptom
Thermostat shows much higher or lower room temperature than actual, but no sensor error code is displayed.
Temperature Calibration Drift
Symptom
Thermostat shows Wi‑Fi connected but cannot be controlled from the Baxi mobile app.
Account Linking / App Control Failure
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E01 |
Thermostat display shows E01 and cannot communicate with the boiler; heating does not start.
|
Boiler Communication Failure | View Details |
| E02 |
Thermostat shows E02 and will not connect to the internet or Baxi cloud services.
|
Wi‑Fi Connectivity Failure | View Details |
| E03 |
Thermostat displays E03 and shows no temperature reading from the room sensor.
|
Internal Room Temperature Sensor Failure | View Details |
| E04 |
Thermostat shows E04 and cannot detect the external wired sensor (e.g. remote room or floor sensor).
|
External Sensor Circuit Open or Short | View Details |
| E05 |
Thermostat displays E05 and the boiler does not respond to heat demands.
|
Relay Output Failure | View Details |
| E06 |
Thermostat shows E06 and cannot pair with the wireless receiver; no RF link.
|
RF Pairing / Radio Link Failure | View Details |
| E07 |
Thermostat displays E07 and time/programming resets unexpectedly.
|
Internal Backup Power / Memory Fault | View Details |
| E08 |
Thermostat shows E08 and the measured room temperature is clearly incorrect (e.g. 0°C or 99°C).
|
Temperature Sensor Out of Range | View Details |
| E09 |
Thermostat displays E09 and cannot control domestic hot water schedule or temperature.
|
Hot Water Control Channel Failure | View Details |
| E10 |
Thermostat shows E10 and indicates low supply voltage or power fault.
|
Low Voltage / Power Supply Error | View Details |
| E11 |
Thermostat displays E11 and cannot complete firmware update via the Baxi app.
|
Firmware Update Failure | View Details |
| E12 |
Thermostat shows E12 and cannot connect to the Baxi cloud or mobile app even though Wi‑Fi is working.
|
Cloud Service / Server Communication Error | View Details |
| E13 |
Thermostat displays E13 and schedules or settings cannot be saved.
|
Non-Volatile Memory Write Error | View Details |
| E14 |
Thermostat shows E14 and indicates an internal temperature too high; device may shut down.
|
Thermostat Overtemperature Protection | View Details |
| E15 |
Thermostat displays E15 and cannot detect the boiler type or configuration.
|
Auto-Configuration / Boiler Type Detection Error | View Details |
| E16 |
Thermostat shows E16 and indicates a fault with the humidity sensor (if equipped).
|
Internal Humidity Sensor Failure | View Details |
| E17 |
Thermostat displays E17 and cannot read the outdoor temperature from an external sensor or internet source.
|
Outdoor Temperature Source Failure | View Details |
| E18 |
Thermostat shows E18 and indicates an internal clock or time sync error.
|
Real-Time Clock / Time Synchronization Fault | View Details |
| E19 |
Thermostat displays E19 and indicates an internal sensor self-test failure at startup.
|
Self-Diagnostic Hardware Failure | View Details |
| E20 |
Thermostat shows E20 and indicates a zone configuration or multi-zone communication error.
|
Multi-Zone Control Communication Fault | View Details |
| – |
Heating stays on constantly even when thermostat is set low or turned off.
|
Stuck Heating Relay / Permanent Call for Heat | View Details |
| – |
Room temperature overshoots setpoint by several degrees before boiler turns off.
|
Poor Temperature Control / Overshoot | View Details |
| – |
Thermostat appears on but boiler does not fire when heat is requested; no error code on thermostat.
|
No Heat Demand Reaching Boiler | View Details |
| – |
Thermostat batteries drain very quickly (within weeks) on a battery-powered Baxi smart thermostat.
|
Excessive Battery Consumption | View Details |
| – |
Thermostat buttons or touchscreen are unresponsive or respond intermittently.
|
User Interface / Keypad Failure | View Details |
| – |
Thermostat display completely blank; no lights or response.
|
No Power to Thermostat | View Details |
| – |
Thermostat does not follow programmed schedule; heating comes on at wrong times.
|
Scheduling / Programming Fault | View Details |
| – |
Thermostat fails to control underfloor heating correctly; floor gets too hot or too cold.
|
Incorrect Underfloor Heating Configuration | View Details |
| – |
Thermostat frequently loses connection to the receiver; heating cuts in and out unpredictably.
|
Intermittent RF Communication | View Details |
| – |
Thermostat frequently reboots or restarts on its own.
|
Intermittent Power or Firmware Instability | View Details |
| – |
Thermostat or receiver casing is unusually warm to the touch during normal operation.
|
Mild Overheating / High Load Operation | View Details |
| – |
Thermostat or receiver emits a buzzing or humming noise during operation.
|
Electrical Noise / Coil Vibration | View Details |
| – |
Thermostat or receiver has a burnt smell or visible scorch marks.
|
Overheating / Component Burnout | View Details |
| – |
Thermostat shows domestic hot water as ON but hot water does not heat as expected.
|
Hot Water Demand Not Reaching Boiler or Cylinder | View Details |
| – |
Thermostat shows much higher or lower room temperature than actual, but no sensor error code is displayed.
|
Temperature Calibration Drift | View Details |
| – |
Thermostat shows Wi‑Fi connected but cannot be controlled from the Baxi mobile app.
|
Account Linking / App Control Failure | View Details |
No matching codes found
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