High
b8 on Viessmann Vitodens 100-W B1HC-19

Your boiler has temporarily stopped working because it has detected an issue with the sensor that measures the temperature of the exhaust gases coming from the flue.

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

Burner blocked, Lead break, flue gas temperature sensor, Check the sensor (see page 56).

From this model's manual
Verified against the Viessmann/Viessmann Vitodens 100 W B1hc B1kc 19 35 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

b5View →b7View →f0View →

All 29 fault codes on the Vitodens 100-W B1HC-19

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

0C5A101830385051525859A3A9b0b7E3E5F0F1F2F3F4F8F9FAFCFdFF

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