What does the Vaillant S.4 fault code mean?

Your boiler is operating normally and is currently in the process of starting up the burner to provide heat or hot water.

How much does it cost to fix Vaillant error code S.4?

Cost varies. Contact a Gas Safe registered engineer for a quote.

Vaillant S.4 Fault Code: What It Means & How to Fix It

What the manual says

Manufacturer manual

Burner ignited

From this model's manual

Verified against the Vaillant/Vaillant Ecotec Plus installation & service manual.

What causes this fault?

This is not a fault, but rather a status message indicating that the boiler has successfully lit the flame. It confirms that the internal ignition sequence is complete and the unit is now producing heat for your radiators or hot water. You will see this code every time the boiler starts up as part of its normal, healthy operation.

DIY fix possible

This fault may be fixable without an engineer. Check your manual first.

Find a Gas Safe engineer

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Related fault codes

S.0View →S.1View →S.3View →S.7View →S.8View →

All 281 fault codes on the ecoTEC plus

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

con D.000 D.001 D.002 D.003 D.004 D.005 D.006 D.008 D.009 D.010 D.011 D.012 D.013 D.015 D.016 D.017 D.018 D.020 D.021 D.022 D.023 D.025 D.026 D.027 D.028 D.029 D.031 D.033 D.034 D.035 D.036 D.039 D.040 D.041 D.043 D.045 D.047 D.052 D.058 D.060 D.061 D.062 D.064 D.065 D.066 D.067 D.068 D.069 D.070 D.071 D.072 D.073 D.074 D.075 D.077 D.078 D.080 D.081 D.082 D.083 D.084 D.085 D.088 D.090 D.091 D.092 D.093 D.094 D.095 D.096 D.098 D.124 D.125 D.128 D.129 D.145 D.146 D.147 D.156 D.157 D.158 D.159 D.160 D.161 D.162 D.163 D.164 D.166 D.167 D.170 D.171 D.172 D.173 D.174 D.175 D.182 D.185 D.186 D.187 F.000 F.001 F.002 F.003 F.010 F.011 F.012 F.013 F.020 F.022 F.023 F.024 F.025 F.027 F.028 F.029 F.032 F.035 F.040 F.042 F.044 F.047 F.049 F.057 F.061 F.062 F.063 F.064 F.065 F.067 F.068 F.070 F.071 F.072 F.074 F.075 F.076 F.077 F.078 F.080 F.081 F.083 F.084 F.085 F.087 F.088 F.089 F.090 F.092 F.095 F.096 F.097 F.105 F.194 F.195 F.196 F.317 F.318 F.320 F.321 F.322 F.323 F.324 F.325 F.326 F.327 F.330 F.334 F.336 F.337 F.338 F.342 F.343 F.344 F.347 F.363 F.707 F.905 I.003 I.020 I.144 L.016 L.022 L.025 L.032 L.095 L.096 L.097 L.105 L.144 L.194 L.195 L.196 L.319 L.320 L.322 L.343 N.013 N.027 N.032 N.089 N.095 N.096 N.097 N.100 N.144 N.194 N.270 N.317 N.319 N.324 N.343 P.000 P.2 P.008 S.0 S.000 S.1 S.001 S.2 S.002 S.003 S.004 S.005 S.006 S.7 S.007 S.008 S.009 S.10 S.010 S.11 S.011 S.012 S.013 S.014 S.15 S.015 S.016 S.17 S.017 S.019 S.20 S.020 S.021 S.022 S.023 S.024 S.025 S.026 S.027 S.028 S.029 S.030 S.031 S.032 S.034 S.039 S.041 S.042 S.054 S.057 S.059 S.088 S.091 S.092 S.093 S.096 S.097 S.098 S.109 S.175 S.199 S.326 S.328 S.335 S.341 S.599 T.001 T.007

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Your boiler is operating normally and is currently in the process of starting up the burner to provide heat or hot water.

What the manual says

What causes this fault?

DIY fix possible

Avoid the next call-out bill

Related fault codes

All 281 fault codes on the ecoTEC plus

Related guides you might find useful

No hot water but heating works

Is boiler cover worth it?

When to replace your boiler

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