9.1.35 High

Ideal 9.1.35 Fault Code

Also written as 9135 — same fault.

The Ideal 9.1.35 fault code means: your boiler is unable to switch between heating your house and providing hot water because an internal diverter component is stuck or broken.. It appears on 1 Ideal model in our database.

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.

Technical description: 3-Way Valve does not Operate and No DHW

What causes the Ideal 9.1.35 fault?

This fault occurs when the mechanical part responsible for directing hot water to either your taps or your radiators becomes stuck or suffers an electrical failure. The most common reason is that the moving parts inside the valve have become seized by debris in the system water, or the small motor that pushes the valve has burnt out. Because the boiler cannot safely confirm where the heat is going, it stops operating to prevent overheating.

This issue is more frequent in autumn when the heating is turned on for the first time after summer, as the valve can seize up due to months of inactivity.

Typical repair cost £180-£320 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Ideal models that show the 9.1.35 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Ideal 9.1.35 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 27 April 2026