What does fault code F.28 mean in Saunier Duval?

Error: unsuccessful ignition at start-up. The ignition box S4565AF (transformer/ionisation) does not deliver a stable spark or does not allow flame detection, therefore combustion is not established; check HV spark, grounding, and ionisation signal, and test with a contrasting S4565AF.

What does the fault code F.29 mean in Saunier Duval?

Error: flame loss. Intermittent fault of the S4565AF ignition transformer/box causes retries and flame extinction; check continuity and performance of the transformer, presence of HV and ionization reading during operation, and rule out with temporary replacement.

RefurbishedSaunier Duval PCBs (control boards)

Ignition Box Saunier Duval Thelia 30 E Ref. S4565AF

Name: Ignition Box Saunier Duval Thelia 30 E Ref. S4565AF
Brand: Saunier Duval
SKU: CECT30E
Price: 50 EUR
Availability: InStock

50 €VAT includedIn stock · 1 unit

PCB (control board): refurbished spare part that controls the ignition, modulation, and safety features of the boiler. Useful if the boiler does not ignite, locks out, or the display is unresponsive. Reference S4565AF. Includes a one-year warranty and delivery within 2–4 working days in the EU.

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Delivery in 2–4 working days

1-year warranty

14-day return

Technical support

Key Data

Reference: S4565AF
Brand: Saunier Duval
Type of part: PCBs (control boards)
Available units: 1 unit in stock
Status: Refurbished
Warranty: 1 year
Shipping: 2–4 working days (EU)
Return: 14 days

Fault codes related to this part (not the entire boiler). They usually have more possible causes: first rule out electrodes, wiring/connections, and gas supply. Verified with ≥3 sources.

Code	What does it mean?	Cause and diagnosis (this part)
F.28	Fault: unsuccessful ignition on start-up.	The S4565AF ignition box (transformer/ionisation) does not deliver a stable spark or does not allow flame detection, so combustion is not established; check HV spark, grounding, and ionisation signal, and test with a contrasting S4565AF.
F.29	Fault: flame loss.	Intermittent fault of the S4565AF transformer/ignition box causes retries and flame extinction; check continuity and performance of the transformer, presence of HV and ionization reading during operation, and rule out with temporary replacement.

Ignition Box Saunier Duval Thelia 30 E Ref. S4565AF

Key Data

Spare Parts Related Boiler Thelia 30 E