Your boiler is performing a routine internal check on its water pressure sensor and should resume normal operation once finished.

Water pressure sensor self-test. The self-test for the water pressure sensor is activated.

What causes this fault?

This occurs when the boiler's internal computer performs a safety check to ensure it is receiving an accurate reading from the water pressure sensor. It happens automatically to verify that the system is not running dry, which protects the internal components from overheating. Most often, this is just a momentary pause in operation, but if it persists, it may indicate the sensor is sending inconsistent signals or the wiring has become loose.