High
ER 15 + RESET on Johnson Starley Warmcair DW

Your boiler has detected that the water is getting too hot too quickly because it isn't moving through the system properly.

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.

Technical description

Differential over-temp across CH flow/return

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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