Worcester Bosch
Worcester Bosch 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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Boiler Offline
Smart thermostat app reports 'Boiler Offline' or 'Device Offline'; thermostat appears normal but cannot control boiler.
Loss of communication between cloud/app and boiler gateway
Comm Err
Thermostat or boiler display shows 'Comm Err' or communication error; setpoint changes on thermostat do not reach boiler.
Digital communication failure between smart thermostat and boiler interface
Firmware Update Failed
Thermostat or app reports 'Firmware Update Failed'; device may reboot repeatedly or lose some functions.
Incomplete or corrupted firmware installation
Floor Sensor Err
Thermostat configured for underfloor heating shows 'Floor Sensor Err' or similar; floor temperature not displayed.
External floor temperature sensor open or short circuit
Frost Protect Active
Thermostat shows 'Frost Protect Active'; heating runs even when schedule is off and setpoint appears low.
Frost protection mode engaged
Humidity Err
Smart thermostat with humidity feature shows 'Humidity Err' or no humidity reading.
Relative humidity sensor failure
Low Batt
Thermostat displays 'Low Batt', battery icon flashing, or intermittently powers off; heating becomes unresponsive.
Thermostat power supply low due to depleted batteries
No RF
Smart thermostat display shows 'No RF' or radio symbol with a cross; heating does not respond to set temperature.
Loss of RF communication between thermostat and boiler receiver
No Signal
Smart thermostat app or display shows 'No Signal' or cloud icon with a cross; remote control via app not working but local control may still function.
Loss of Wi‑Fi or cloud connectivity
Overheat Protect
Thermostat or underfloor controller shows 'Overheat Protect' or high temperature warning; heating output is disabled.
Over‑temperature protection triggered by sensor reading
Relay Fault
Smart thermostat or receiver shows 'Relay Fault'; heating does not switch on or remains stuck on.
Stuck or failed switching relay in receiver or thermostat
RF Pairing Failed
During setup, thermostat shows 'RF Pairing Failed' or cannot complete binding with receiver.
RF pairing process unsuccessful
Schedule Err
Thermostat displays 'Schedule Err' or refuses to save new schedules; heating runs at unexpected times.
Corrupted schedule data or memory write failure
Sensor Err
Thermostat shows 'Sensor Err', 'SENS', or a similar message; room temperature reading is blank or shows dashes.
Room temperature sensor failure or disconnection
Service Due
Thermostat displays 'Service Due' or wrench icon; heating still operates normally.
Scheduled boiler service reminder
Time Sync Err
Smart thermostat shows incorrect time or 'Time Sync Err'; schedules run at wrong times.
Clock synchronization failure with server or internal RTC fault
Valve Err
Smart zoning thermostat or wiring centre shows 'Valve Err'; associated zone does not heat.
Motorised zone valve control fault
Zone Config Err
Multi‑zone smart system shows 'Zone Config Err' or similar; some zones do not follow schedules.
Incorrect zone configuration or addressing
Symptom
Boiler fires but radiators do not get hot in the zone controlled by the smart thermostat.
Flow control or zoning fault
Symptom
Condensation or moisture visible inside thermostat cover.
Moisture ingress
Symptom
Heating does not come on even when thermostat is set well above room temperature.
No call for heat from thermostat to boiler
Symptom
Heating stays on constantly even when thermostat is set low or turned off.
Stuck call for heat
Symptom
Room temperature reading is clearly wrong (e.g. shows 10°C when room feels warm).
Room temperature sensor miscalibration or failure
Symptom
Smart thermostat schedules randomly reset or revert to default.
Non‑volatile memory instability
Symptom
Thermostat buttons or touchscreen unresponsive or intermittently working.
User interface input failure
Symptom
Thermostat cannot be added to the Worcester Bosch app during setup.
Provisioning or pairing failure with cloud account
Symptom
Thermostat display completely dead; no backlight or response to buttons.
Thermostat power loss
Symptom
Thermostat fails to control domestic hot water schedule on a system where it should.
Hot water control configuration fault
Symptom
Thermostat frequently loses connection to app or shows intermittent offline status.
Unstable network connectivity
Symptom
Thermostat frequently reboots or restarts on its own.
Unstable internal power or firmware crash
Symptom
Thermostat makes clicking or buzzing noises frequently.
Relay chatter or electrical noise
Symptom
Thermostat or receiver has a burnt smell or visible scorch marks.
Overheated electronic component
Symptom
Thermostat plastic housing becomes noticeably warm to the touch.
Internal component heating
Symptom
Thermostat screen is very dim or unreadable, but heating still responds.
Backlight or LCD degradation
Symptom
Thermostat shows correct temperature but boiler cycles on and off very frequently.
Short cycling due to control settings
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| Boiler Offline |
Smart thermostat app reports 'Boiler Offline' or 'Device Offline'; thermostat appears normal but cannot control boiler.
|
Loss of communication between cloud/app and boiler gateway | View Details |
| Comm Err |
Thermostat or boiler display shows 'Comm Err' or communication error; setpoint changes on thermostat do not reach boiler.
|
Digital communication failure between smart thermostat and boiler interface | View Details |
| Firmware Update Failed |
Thermostat or app reports 'Firmware Update Failed'; device may reboot repeatedly or lose some functions.
|
Incomplete or corrupted firmware installation | View Details |
| Floor Sensor Err |
Thermostat configured for underfloor heating shows 'Floor Sensor Err' or similar; floor temperature not displayed.
|
External floor temperature sensor open or short circuit | View Details |
| Frost Protect Active |
Thermostat shows 'Frost Protect Active'; heating runs even when schedule is off and setpoint appears low.
|
Frost protection mode engaged | View Details |
| Humidity Err |
Smart thermostat with humidity feature shows 'Humidity Err' or no humidity reading.
|
Relative humidity sensor failure | View Details |
| Low Batt |
Thermostat displays 'Low Batt', battery icon flashing, or intermittently powers off; heating becomes unresponsive.
|
Thermostat power supply low due to depleted batteries | View Details |
| No RF |
Smart thermostat display shows 'No RF' or radio symbol with a cross; heating does not respond to set temperature.
|
Loss of RF communication between thermostat and boiler receiver | View Details |
| No Signal |
Smart thermostat app or display shows 'No Signal' or cloud icon with a cross; remote control via app not working but local control may still function.
|
Loss of Wi‑Fi or cloud connectivity | View Details |
| Overheat Protect |
Thermostat or underfloor controller shows 'Overheat Protect' or high temperature warning; heating output is disabled.
|
Over‑temperature protection triggered by sensor reading | View Details |
| Relay Fault |
Smart thermostat or receiver shows 'Relay Fault'; heating does not switch on or remains stuck on.
|
Stuck or failed switching relay in receiver or thermostat | View Details |
| RF Pairing Failed |
During setup, thermostat shows 'RF Pairing Failed' or cannot complete binding with receiver.
|
RF pairing process unsuccessful | View Details |
| Schedule Err |
Thermostat displays 'Schedule Err' or refuses to save new schedules; heating runs at unexpected times.
|
Corrupted schedule data or memory write failure | View Details |
| Sensor Err |
Thermostat shows 'Sensor Err', 'SENS', or a similar message; room temperature reading is blank or shows dashes.
|
Room temperature sensor failure or disconnection | View Details |
| Service Due |
Thermostat displays 'Service Due' or wrench icon; heating still operates normally.
|
Scheduled boiler service reminder | View Details |
| Time Sync Err |
Smart thermostat shows incorrect time or 'Time Sync Err'; schedules run at wrong times.
|
Clock synchronization failure with server or internal RTC fault | View Details |
| Valve Err |
Smart zoning thermostat or wiring centre shows 'Valve Err'; associated zone does not heat.
|
Motorised zone valve control fault | View Details |
| Zone Config Err |
Multi‑zone smart system shows 'Zone Config Err' or similar; some zones do not follow schedules.
|
Incorrect zone configuration or addressing | View Details |
| – |
Boiler fires but radiators do not get hot in the zone controlled by the smart thermostat.
|
Flow control or zoning fault | View Details |
| – |
Condensation or moisture visible inside thermostat cover.
|
Moisture ingress | View Details |
| – |
Heating does not come on even when thermostat is set well above room temperature.
|
No call for heat from thermostat to boiler | View Details |
| – |
Heating stays on constantly even when thermostat is set low or turned off.
|
Stuck call for heat | View Details |
| – |
Room temperature reading is clearly wrong (e.g. shows 10°C when room feels warm).
|
Room temperature sensor miscalibration or failure | View Details |
| – |
Smart thermostat schedules randomly reset or revert to default.
|
Non‑volatile memory instability | View Details |
| – |
Thermostat buttons or touchscreen unresponsive or intermittently working.
|
User interface input failure | View Details |
| – |
Thermostat cannot be added to the Worcester Bosch app during setup.
|
Provisioning or pairing failure with cloud account | View Details |
| – |
Thermostat display completely dead; no backlight or response to buttons.
|
Thermostat power loss | View Details |
| – |
Thermostat fails to control domestic hot water schedule on a system where it should.
|
Hot water control configuration fault | View Details |
| – |
Thermostat frequently loses connection to app or shows intermittent offline status.
|
Unstable network connectivity | View Details |
| – |
Thermostat frequently reboots or restarts on its own.
|
Unstable internal power or firmware crash | View Details |
| – |
Thermostat makes clicking or buzzing noises frequently.
|
Relay chatter or electrical noise | View Details |
| – |
Thermostat or receiver has a burnt smell or visible scorch marks.
|
Overheated electronic component | View Details |
| – |
Thermostat plastic housing becomes noticeably warm to the touch.
|
Internal component heating | View Details |
| – |
Thermostat screen is very dim or unreadable, but heating still responds.
|
Backlight or LCD degradation | View Details |
| – |
Thermostat shows correct temperature but boiler cycles on and off very frequently.
|
Short cycling due to control settings | View Details |
No matching codes found
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