Ferroli F11 Fault Code (i25 / i29)

Safety disclaimer

Fault code summary

Manufacturer

Ferroli

Fault code

F11

Fault type

Temperature sensor, Hot water

Severity

temporary

Reset

Ferroli states that F faults reset automatically when the value returns to the normal range.

Applicable models

Ferroli i25, Ferroli i29

Quick answer

Domestic-hot-water sensor fault.

What does this fault code mean?

Domestic-hot-water sensor fault.

Common causes

• Sensor damaged.
• Wiring shorted.
• Wiring disconnected.

Symptoms

• The display flashes F11 and hot-water operation may pause.

What can the homeowner safely check?

• Record the code and contact the installer.

Boiler reset information

Ferroli states that F faults reset automatically when the value returns to the normal range.

When should I call an engineer?

Contact a suitably qualified heating engineer when the fault persists, the boiler locks out, or the manufacturer instructions do not resolve it. For gas appliance work in the UK, use a Gas Safe registered engineer.

Engineer diagnosis

• Test the DHW sensor and its wiring.

Applicable boiler models

• Ferroli i25
• Ferroli i29

Related fault codes

• A01 — i25 / i29

  No burner ignition.

  Read fault code
• A02 — i25 / i29

  Flame-present signal with the burner off.

  Read fault code
• A03 — i25 / i29

  Overtemperature protection intervention.

  Read fault code
• A06 — i25 / i29

  No flame after the ignition phase.

  Read fault code
• A09 — i25 / i29

  Gas-valve fault.

  Read fault code
• A15 — i25 / i29

  Air-pressure-switch fault F05 generated five times in the last 24 hours.

  Read fault code
• A16 — i25 / i29

  Gas-valve fault.

  Read fault code
• A23 — i25 / i29

  Card parameter fault.

  Read fault code

Manufacturer documentation

Table 9: F11 — DHW sensor fault; causes sensor damaged, wiring shorted or wiring disconnected.

Last verified

2026-09-12

Frequently asked questions