Your boiler's internal wiring has been connected incorrectly, causing it to confuse high and low pressure readings.

High Pressure Sensor and Low Pressure Sensor Wiring Reversed

What causes this fault?

This fault occurs when the electrical wires for the high and low pressure sensors have been swapped or plugged into the wrong terminals on the main control board. The boiler detects that the readings are the opposite of what is expected, causing it to shut down for safety. This is usually the result of a manufacturing error or a mistake made during a recent repair or part replacement.