High
F01 on Glow-worm Ultracom 2 35cxi

Your boiler has stopped working because a sensor that monitors the temperature of the water returning to the system is reading incorrectly or has disconnected.

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

Return heating temperature sensor fault

From this model's manual
Verified against the Glow Worm/Glow Worm Ultracom2 24cxi 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 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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All 33 fault codes on the Ultracom 2 35cxi

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

ErrF00F10F11F20F22F23F24F26F27F28F29F32F49F61F62F63F64F65F67F68F70F71F72F73F74F76F77F83F84F85F86

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