BoilerFaultCodesIdeal -. / Y Fault Code
Also written as Y — same fault.
The Ideal -. / Y fault code means: your boiler is stuck on the heating setting and cannot control its temperature properly, leading to overheating or a lack of hot water.. It appears on 1 Ideal model in our database.
Technical description: Unit is constantly fired for the central heating and does not modulate in reverse direction. The central heating installation is overheated or not sufficiency heated; the hot water tank is not heated. Unit is constantly operative for the central heating, at the capacity adjusted with the hot water potentiometer.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Avoid the next call-out bill
A cover plan would handle faults like -. / Y: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.
Ideal models that show the -. / Y fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal -. / Y fault code information on this page is sourced and cross-checked against the official Ideal service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026