What does the Unical 43 fault code mean?

Your boiler is failing to keep a stable flame lit during startup, which causes it to safely shut down to prevent gas from building up.

How much does it cost to fix Unical error code 43?

Typical repair cost for the Unical 43 fault is £150-350 including labour.

Unical 43 Fault Code: What It Means & How to Fix It

What the manual says

Manufacturer manual

During the ignition stage, abnormal flame extinguishing has occurred 12 "consecutive" times in a period of about 50 / sec. Check the gas pressure / any flue gas recirculation in the chimney and obstructions / condensation drain / electrode electrical connection / electrode and burner earth / perform GAC calibration chap. 4.3.1 / replace the electrode and its connection / replace the electronic board

From this model's manual

Verified against the Unical/Unical Alkon C 28 He installation & service manual.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Find a Gas Safe engineer

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Boiler cover options

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A cover plan would handle faults like 43: no call-out fees, no surprise bills.

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All 33 fault codes on the Alkon C 28 HE

Seeing a different code? Every code this model can display, in one place.

1 4 5 6 8 09 11 12 13 14 15 16 17 18 20 21 22 23 24 26 27 30 32 33 38 44 45 53 55 75 80 81

Your boiler is failing to keep a stable flame lit during startup, which causes it to safely shut down to prevent gas from building up.

What the manual says

Engineer required

Avoid the next call-out bill

All 33 fault codes on the Alkon C 28 HE

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