AL40 High

Vokera AL40 Fault Code

The Vokera AL40 fault code means: your boiler has stopped working because the water pressure in the central heating system is too low.. It appears on 12 Vokera models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Check the system’s pressure and refill if necessary. Reset the boiler, if the fault reoccurs then you need to contact a heating engineer.

What causes the Vokera AL40 fault?

This fault occurs when the water levels inside your heating system drop below a safe operating limit, preventing the boiler from firing up to avoid damage. The most common reasons are a small leak somewhere in your radiator circuit or the need to bleed air from your radiators, which reduces the overall pressure. In some cases, a component inside the boiler like the expansion vessel may have failed, losing its ability to maintain steady pressure.

This fault is frequently seen in autumn when homeowners turn their heating back on for the first time after summer, revealing pressure drops that occurred while the system was idle.

Typical repair cost £0-120 (including labour)

DIY fix possible

Locate the filling loop (usually a silver braided hose with small valves underneath the boiler).Slowly open the valve(s) until you hear water entering the system and the pressure gauge reaches between 1 and 1.5 bar.Close the valves tightly and press the reset button on the boiler control panel.

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Vokera models that show the AL40 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Vokera AL40 fault code information on this page is sourced and cross-checked against the official Vokera service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026