E04
Tado
Heating System Detection or Configuration Error
Smart thermostat shows E04 and cannot detect the heating system type during setup.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Unsupported boiler communication protocol, Incorrect wiring to digital bus terminals, Misconfigured system type in Tado app, Faulty boiler communication interface
How to Fix / Troubleshooting
Safety warning: Boiler terminals may carry low-voltage but can be adjacent to mains. Turn off boiler power before rewiring.
- Verify boiler compatibility: Check Tado’s online compatibility tool with your boiler model to confirm supported control methods (e.g., relay, OpenTherm, eBUS).
- Check wiring type: If using digital bus (e.g., OpenTherm), ensure the two bus wires are connected to the correct Tado terminals and not mixed with 230 V switching lines.
- Reconfigure in app: In the Tado app, go to device settings > installation and confirm the selected system type (e.g., combi boiler, system boiler with hot water). Correct any mismatches.
- Test with simple relay mode: If digital communication fails, temporarily configure Tado to use simple on/off relay control (if supported by your boiler) and wire COM/NO accordingly. This can bypass protocol issues.
- Power cycle boiler: After changes, turn the boiler off for 30 seconds and back on to reset its control interface, then repeat the Tado setup.
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Repair Difficulty
Medium
3/5
Required Part
Tado Smart Thermostat Communication Terminals
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