High
uP on Ideal Logic Combi ESP1

Your boiler is currently stuck in its internal computer programming mode and hasn't been set up to operate as a heater yet.

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

Display shows uP on power on (PCB programming mode)

Shared across the Logic Combi range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This fault occurs when a newly installed or replacement control board has not been told which specific boiler model it is living in. Because the same board is used across many different models, it remains in a 'blank' programming mode and refuses to fire until the correct configuration code is entered. The most common reason is that a technician has just replaced the board but hasn't finished the final software setup.

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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Related fault codes

L2View →F2View →

All 34 fault codes on the Logic Combi ESP1

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

00DUF1F2F2 or Fn or LnF3F4F4 or L4F5F5 or L5F6F7F8F9F9 or L9 or F8 or L8FAFnFUL1L2L4L4 or F4L5L5 or F5L6L8L9LCLnoFSHSLUF

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