BoilerFaultCodesYour boiler has lost connection with the sensor that monitors the outdoor temperature, which may cause your heating to behave unpredictably.
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: Kontaktfehler oder defekter Außenfühler
What causes this fault?
This fault occurs when the boiler can no longer communicate with the sensor located on the outside of your property. The most common reasons are loose electrical connections, corroded sensor terminals due to weather exposure, or a physical break in the wiring connecting the sensor to the boiler.
This fault often comes to light during autumn or winter when the heating is first turned on and the boiler tries to adjust its settings based on the cold outdoor temperature.
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 TA 211 E 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.