Low
d.81 on Vaillant ecoMAX

This code is not an actual fault; it is simply an information display showing the total number of hours your boiler has spent providing hot water.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

Number of hot water system operating hours (Total) (ecoMAX 800)

From this model's manual
Verified against the Vaillant Ecomax installation & service manual, page 47.
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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