What does the Ideal 4Y fault code mean?

Your boiler has lost its connection to the internal thermometer that monitors water temperature, meaning it cannot safely heat your home or water.

How much does it cost to fix Ideal error code 4Y?

Typical repair cost for the Ideal 4Y fault is £90-180 including labour.

Ideal 4Y Fault Code: What It Means & How to Fix It

What the manual says

Manufacturer manual

Supply sensor not connected.

Shared across the Maximiser SE 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.

What causes this fault?

This fault occurs when the boiler's main computer loses communication with the temperature sensor attached to the internal pipework. It is usually caused by the sensor failing due to age, or a loose connection or damaged wire preventing the signal from reaching the control board.

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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Boiler cover options

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All 118 fault codes on the Maximiser SE

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

-. / A -. / H -. / Y -. H =. / H =. H 0 / A 0 / H 0 / Y 0 or -. / H 0A 0H 0L 0U 0Y 001 01 1 / C 1C 2 / C 2 / F 2 / P 2 / U 2C 2F 2P 2U 03 004 4 / A 4 / C 4 / F 4 / L 4 / P 4 / U 4 / Y 4A 4C 4F 4L 4P 4U 005 05 5 / A 5 / Y 5A 5Y 6 / A 6 / C 6 / H 6 / L 6A 6C 6H 6L 7 / A 7A 7C 7F 7H 7L 008 8L 9A 9C 9F 9H 9L 9P 9U 010 10 011 12 13 14 15 016 16 017 17 18 018 19 20 21 23 24 25 26 27 28 29 029 30 31 32 34 35 36 37 38 39 40 41 041 42 43 60 EA EC EF EH EL EP No display

Your boiler has lost its connection to the internal thermometer that monitors water temperature, meaning it cannot safely heat your home or water.

What the manual says

What causes this fault?

Engineer required

Avoid the next call-out bill

All 118 fault codes on the Maximiser SE

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