Viessmann EE Fault

Viessmann EE Fault

When the Viessmann EE fault code appears, it means that the boiler’s control system has detected an external fault. In this case, the external fault can be as a result of an external control device like a thermostat, or sensor that is connected to the boiler but which is not operating according to its expected parameters.
Causes of the EE Fault Code

Faulty External Thermostat or Sensor: An improperly installed or malfunctioning external thermostat or sensor linked to the boiler may lead to incorrect signals going into the boiler hence producing an error code labeled as EE.

Wiring Issues: Problems with wiring connections between any of these and the boiler might interrupt communication thereby leading to an external fault in the boiler.

Incompatible External Controls: The presence of incompatible devices working outside their settings in respect to system compatibility can cause EE fault failure alert by your Viessmann.

External Energy Management System Issues: If there are faults on this system that operates outside, then you might expect your boiler display ‘EE’ fault code on its screen.

Troubleshooting and Resolving the EE Fault Code

Inspect External Devices: Check for signs of damage or malfunction on any externally attached thermostats, sensors, or control devices. Ensure installation correctness and manufacturer specifications through configuration checks.

Check Wiring Connections: Check all wire links between a heat generator and external devices thoroughly. Observe any signs such as wear out damages loose contacts that may deter clear communications in-between them.

Test External Devices: Establish whether they operate well by testing some peripherals such as outdoor temperature sensors. This could involve using diagnostic tools or swapping them temporarily with known good working units.

Review Device Compatibility: All these should be compatible with it said device but incase one is unsure about this information from manufacturer’s manual can always come handy when talking with a Viessmann technician about this issue.

Resetting Boiler: Resetting will ensure normal directions are followed after remedying problems arising from outside equipment and connections, thus it is possible to reboot the system from scratch.

Consult a Professional: For example, if you can’t trace where an external problem lies, then contact a Gas Safe registered engineer or a Viessmann certified technician. This will help in resolving complex issues arising from outside faults and at the same time giving a detailed diagnosis.


This error code indicates that your boiler’s connection with an external device or control has malfunctioned. To fix this issue, one must check and test any connected thermostats, sensors or control devices externally while ensuring proper wiring and compatibility of devices. Given the complexities associated with diagnosing external faults, getting professional assistance may be necessary for accurate identification and resolution of such problems hence optimal performance of the heating equipment.