Low
E15 on Warmflow Agentis Internal

Your boiler's internal sensor that monitors the temperature of the water returning from your radiators has developed a fault or become disconnected.

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

CH Return NTC Error — CH return NTC temperature sensor short circuit or disconnected (logged only, not shown on LCD); consult Service Engineer

From this model's manual
Verified against the Warmflow Agentis Internal installation & service 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 fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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