Low
dP on Johnson Starley Warmcair DW

Your boiler is currently running at its maximum power setting because a service mode used for testing has been activated.

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

Maximum combustion rate (indicating sweep test mode)

From this model's manual
Verified against the Johnson Starley Warmcair Dw 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.

DIY fix possible

Check if the 'Test' or 'Sweep' button has been pressed or held down accidentally.Turn the boiler power off at the fused spur switch, wait 30 seconds, and turn it back on to reset the electronics.Ensure the control dials are moved away from any maximum test positions.

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