Medium
N.027 on Vaillant ecoTEC Plus 836

Your boiler is struggling to accurately measure the temperature of the water used for your taps and shower, which will likely result in the water being cold or failing to heat up at all.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Temperature sensor defective. The signal for the temperature sensor on the domestic hot water connection is implausible.

From this model's manual
Verified against the Vaillant Ecotec Plus installation & service manual, page 93.
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 fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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