43 mm Low

Ferroli 43 mm Fault Code

Also written as 43MM — same fault.

The Ferroli 43 mm fault code means: this is a technical configuration setting for your boiler's flue rather than a system fault, indicating the specific size of the air restrictor plate required for your flue pipe setup.. It appears on 1 Ferroli model in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Restrictor size for Concentric 1 bend + 1 meter

Engineer required

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

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →
Boiler cover options

Avoid the next call-out bill

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

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Ferroli models that show the 43 mm fault code

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

Source

Ferroli 43 mm fault code information on this page is sourced and cross-checked against the official Ferroli service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026