What does the Viessmann CF fault code mean?

Your boiler is having trouble 'talking' to its internal Wi-Fi or internet connection module, which may prevent you from controlling it via apps or external thermostats.

How much does it cost to fix Viessmann error code CF?

Typical repair cost for the Viessmann CF fault is £100-350 including labour.

Viessmann CF Fault Code: What It Means & How to Fix It

What the manual says

Manufacturer manual

Communications fault-LON communication module

From this model's manual

Verified against the Viessmann/Viessmann Vitodens 300 Wb3a 49 66kw 5862570 installation & service manual.

What causes this fault?

This fault occurs when the boiler's main control board loses its digital connection with the internal Wi-Fi or communication module. It is usually caused by a loose wiring plug, a software glitch in the module, or a hardware failure on the communication board itself.

DIY fix possible

Turn the boiler off at the main power switch for 30 seconds, then turn it back on to reboot the electronics.Check your home internet router is working correctly and within range of the boiler.Verify that any external smart thermostats or bridges are powered on and connected.

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Related fault codes

C7View →F0View →

All 90 fault codes on the Vitodens 300 WB3A 49kW

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

00:1 00:2 00:3 00:5 00:6 0F 1A 04 06 06:...07 08 9A 9b 9B 9C 9F 10 18 20 23:0 25 26 28 30 30:0 35 38 40 48 50 51 58 58:0 59 60 68 80:0 92 93 94 97:2 A2 A2:0 A5 A7 A8 A9 b0 b1 b4 b5 b7 b8 bA bc bC bd be bE bF C2 C5 C6 C7 Cd CE d2 dA db dE E4 E5 E6 EL F0 F1 F2 F3 F4 F5 F7 F8 F9 FA Fd FE Filling Venting

Your boiler is having trouble 'talking' to its internal Wi-Fi or internet connection module, which may prevent you from controlling it via apps or external thermostats.

What the manual says

What causes this fault?

DIY fix possible

Avoid the next call-out bill

Related fault codes

All 90 fault codes on the Vitodens 300 WB3A 49kW

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