What does the Vaillant S.1 fault code mean?

Your boiler is trying to start up but the internal fan is not spinning properly, preventing the heating from firing up.

How much does it cost to fix Vaillant error code S.1?

Typical repair cost for the Vaillant S.1 fault is £250-£550 including labour.

Vaillant S.1 Fault Code: What It Means & How to Fix It

What the manual says

Manufacturer manual

Fan start-up error

From this model's manual

Verified against the Vaillant/Vaillant Ecotec 65kw installation & service manual, page 34.

What causes this fault?

This fault occurs when the boiler's control system sends a signal to the fan to begin spinning, but it fails to reach the required speed to safely start the ignition process. The most common reasons are a build-up of debris or moisture inside the fan casing, or a communication failure between the main control board and the fan motor.

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.

Find a Gas Safe engineer

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Boiler cover options

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Related fault codes

S.2View →S.3View →

All 122 fault codes on the ecoTEC plus VU GB 656/4-5 A

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

D.0 D.1 D.2 D.4 D.5 D.7 D.8 D.9 D.10 D.11 D.12 D.13 D.14 D.15 D.17 D.18 D.20 D.22 D.23 D.25 D.26 D.27 D.28 D.30 D.33 D.34 D.40 D.41 D.44 D.47 D.50 D.51 D.60 D.61 D.64 D.65 D.67 D.68 D.69 D.71 D.72 D.75 D.76 D.77 D.78 D.80 D.81 D.82 D.83 D.84 D.90 D.91 D.93 D.96 D.97 D.98 F.0 F.1 F.10 F.11 F.13 F.20 F.22 F.23 F.24 F.27 F.28 F.29 F.32 F.49 F.61 F.62 F.63 F.64 F.65 F.67 F.70 F.71 F.72 F.73 F.74 F.75 F.77 P.0 P.1 P.2 P.5 P.6 S.0 S.2 S.3 S.4 S.5 S.6 S.7 S.8 S.20 S.21 S.22 S.23 S.24 S.25 S.26 S.27 S.28 S.30 S.31 S.32 S.34 S.36 S.39 S.41 S.42 S.53 S.54 S.59 S.85 S.96 S.97 S.98 S.O

Your boiler is trying to start up but the internal fan is not spinning properly, preventing the heating from firing up.

What the manual says

What causes this fault?

Engineer required

Avoid the next call-out bill

Related fault codes

All 122 fault codes on the ecoTEC plus VU GB 656/4-5 A

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