BoilerFaultCodesWhat the manual says
Manufacturer manual(837/637 only) | Main heat exchanger anti freeze protection mode due to no switching signal from the air pressure switch | Check air pressure switch, fan, fan supply or flue system
From this model's manual
Verified against the Vaillant/Vaillant Turbomax Plus 824 828e installation & service manual, page 40.
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
All 92 fault codes on the Turbomax Plus 828
Seeing a different code? Every code this model can display, in one place.
d.00d.01d.02d.05d.07d.08d.10d.11d.21D.22d.23D.24d.25d.30d.33d.34d.35d.37d.40d.41d.50d.60d.61d.64d.65d.67d.68d.69d.71d.72d.73d.75d.76d.80d.81d.82d.83F 22F.00F.01F.10F.11F.20F.22F.23F.24F.27F.28F.29F.32F.37F.41F.42F.43F.60F.61F.62F.63F.64F.65F.66F.67S.00S.01S.02S.03S.04S.05S.07S.08S.10S.11S.13S.14S.16S.17S.20S.21S.23S.24S.27S.28S.30S.31S.32S.33S.34S.36S.39S.53S.54