BoilerFaultCodesWorcester Bosch Fault 33 22 Fault Code
Also written as FAULT3322 — same fault.
The Worcester Bosch Fault 33 22 fault code means: your boiler has stopped working because its internal control board has detected that some wiring or sensors have been plugged into the wrong ports during a service or repair.. It appears on 2 Worcester Bosch models in our database.
Technical description: A temperature sensor is connected to the IUM. Temperature sensors incorrectly connected.
What causes the Worcester Bosch Fault 33 22 fault?
This fault usually happens following a recent repair or service where the internal wiring has been disturbed. It occurs because the boiler's control board detects that critical temperature sensors have been plugged into the wrong terminals, or the communication module has been incorrectly configured. Because the boiler cannot accurately monitor temperatures, it shuts down as a safety precaution to prevent overheating.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Worcester Bosch models that show the Fault 33 22 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch Fault 33 22 fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026