BoilerFaultCodesIdeal E35 Fault Code
The Ideal E35 fault code means: your boiler has sensed a flame after it should have gone out, or before it has even started, causing it to shut down for safety.. It appears on 6 Ideal models in our database.
Technical description: Flame detection error (parasite flame)
What causes the Ideal E35 fault?
This fault occurs when the boiler’s internal control system thinks a flame is present even though it shouldn't be burning. The most common reason is a sensor that has become dirty or faulty, or a gas valve that is slightly leaking and allowing a small amount of fuel to keep a flame going. In some cases, the electronic control board may simply be misreading the electrical signals from the burner.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Ideal models that show the E35 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal E35 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