Worcester Bosch Hot Water Temperature Sensor Fault (DHW NTC)

Boiler displays A7, hot water temperature is erratic or incorrect.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Faulty DHW NTC sensor, Loose sensor connection on plate heat exchanger, Damaged wiring harness, PCB sensor input fault

Safety first: Isolate power before removing any covers. Domestic hot water can become excessively hot if the sensor fails.

Reset boiler: Try a single reset to clear any transient error.
Check for leaks: Look around the plate heat exchanger and DHW pipework for any leaks that may affect the sensor.
Engineer tasks: A Gas Safe engineer should test the DHW NTC resistance, inspect and reseat the connector, and replace the sensor or PCB if readings are out of range.

Hard 4/5

DHW Temperature Sensor (NTC)

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