BoilerFaultCodesYour boiler has detected a problem with one of its internal temperature sensors, which prevents it from heating your home or water safely.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Sensor fault S2
What causes this fault?
This fault occurs when the boiler's internal computer receives an incorrect or missing signal from the return temperature sensor. The most common reason is that the sensor itself has worn out and failed, though it can also be caused by loose wiring or water damage to the electrical connections inside the casing.
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 24 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
Affiliate links — we may earn a commission at no extra cost to you.