Er.13 Medium

Boiler Fault Code Er.13

Also written as ER13 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code Er.13 appears across 2 boiler brands and 4 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is struggling to switch between heating your radiators and heating your hot water taps, which may cause your hot water to stop working or your radiators to get hot when they shouldn't. (As reported on Vaillant Turbomax Pro 28 2E)

Pick your boiler brand for the Er.13 fix

Source

Information for the Er.13 fault code is sourced from the official service / installation manual for each model that displays it. Read more about how we source fault codes →

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