BoilerFaultCodesUnical 13 Fault Code
The Unical 13 fault code means: your boiler is struggling to detect the temperature of your hot water, which means it will likely stop producing hot water until the faulty sensor is fixed.. It appears on 2 Unical models in our database.
Technical description: DOMESTIC HOT WATER SENSOR Domestic hot water sensor fault (1) (Par.4) or its connections.
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 →Avoid the next call-out bill
A cover plan would handle faults like 13: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.
Unical models that show the 13 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Unical 13 fault code information on this page is sourced and cross-checked against the official Unical service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026