High
E099 on Vokera Vision Plus 35C/40C

Your boiler has detected that the water is not circulating between the heating pipes as expected, causing the system to shut down to prevent overheating.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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.

What the manual says

Manufacturer manual

outlet/return line probe differential alarm

Shared across the Vision Plus range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
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 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

E04View →E05View →

All 24 fault codes on the Vision Plus 35C/40C

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

<0,6 bar>3,0 barCOMCOM1COMPE010E011E020E030E040E041E042E060E070E077E080E084E086E090E091FWEROBCDOTER

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