BoilerFaultCodesYour boiler is reporting a minor sensor issue related to your solar hot water system, but it is not a breakdown of the central heating itself.
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: Cylinder temperature bottom: Is only displayed, if a solar module is connected.
What causes this fault?
This fault occurs when the boiler loses communication with the sensor located at the bottom of your solar hot water cylinder. The most common reason is a faulty temperature sensor (NTC) or a break in the wiring connecting the solar control module to the tank. While your central heating will continue to work, the system can no longer monitor how much free heat is being provided by your solar panels.
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 →Protect yourself from future repair bills
A boiler cover plan would cover faults like 1-d2 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.