High
73 on Viessmann Vitodens 200-W B2HB-35

Your boiler has detected a communication fault with one of its connected add-on parts, so it is stopping itself from firing up to heat your home or water until an engineer can check it.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

What the manual says

Manufacturer manual

Feedback input from internal H1 extension prevents burner start.

From this model's manual
Verified against the Viessmann/Viessmann Vitodens 200 W B2hb B2kb 5792013 installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

72View →77View →61View →

All 89 fault codes on the Vitodens 200-W B2HB-35

Seeing a different code? Every code this model can display, in one place.

9A9b9C9E9F101819202830385051585970717475768080/EE8181/EE8282/EE838485909192939495969899A3A7A9B0b1b5b7B8bFC1C2C3C4C5CdCFd3d4d5d6d7d8E0E1E2E3E4E5E7E8E9EAEbECEdEEEFF0F1F2F3F8F9FAFbFCFdFEFF

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