BoilerFaultCodesWorcester Bosch INDICATOR LIGHT FLASHING Fault Code
Also written as INDICATORLIGHTFLASHING — same fault.
The Worcester Bosch INDICATOR LIGHT FLASHING fault code means: your boiler has detected a problem with one of its internal temperature sensors and has stopped working as a safety precaution.. It appears on 1 Worcester Bosch model in our database.
Technical description: Sensor fault.
What causes the Worcester Bosch INDICATOR LIGHT FLASHING fault?
This fault occurs when the internal temperature sensors, which monitor how hot the water is getting, fail to send a reliable signal to the boiler's brain. The most common reason is that the sensor has physically degraded or developed a chemical build-up over time, causing it to provide inaccurate readings. In some cases, the electrical wiring connecting these sensors has become loose or damaged, leading the boiler to shut down 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 INDICATOR LIGHT FLASHING fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch INDICATOR LIGHT FLASHING 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