BoilerFaultCodesYour boiler has lost its connection to the outside temperature sensor, which helps it run efficiently.
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: Break in communication with the outdoor sensor
What causes this fault?
This fault occurs when the boiler can no longer receive data from the sensor mounted on the outside of your home. The most common reason is a physical break in the low-voltage wiring connecting the sensor to the boiler, often caused by accidental damage or degradation over time. It can also happen if the sensor itself has developed a fault or if water has managed to get inside the sensor's 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 CC — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Worcester Bosch R30 35 And 40 HE Plus is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.