BoilerFaultCodesYour boiler's solar heating sensor has detected an unusually high temperature or a technical fault, causing the system to stop as a precaution.
This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.
Technical description: Collector temperature sensor (T1) fitted on collector array inlet.
What causes this fault?
This fault occurs when the sensor on your roof's solar panels detects that the fluid has become too hot or if the sensor itself has developed an electrical failure. It is often caused by a lack of fluid circulation in the solar circuit or a degraded sensor that is sending incorrect temperature readings to the boiler.
This fault is most common during the summer months when high levels of solar radiation can lead to the solar fluid overheating if the system isn't circulating correctly.
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 53125 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.