The boiler displays E07; this may indicate a return temperature sensor error.

Safety: Disconnect power before working inside the boiler cabinet.

• Locate return sensor: Find the return temperature sensor on the return manifold or pipe entering the Crown boiler.
• Inspect connection: Verify that the sensor plug is fully inserted into the control board and that the contacts are clean.
• Check cable routing: Ensure the cable is not pinched by the boiler casing or in contact with hot surfaces that could melt insulation.
• Verify sensor placement: If the sensor is in a well, confirm it is fully inserted and secured.
• Reset: After inspection, restore power and reset the boiler. Persistent E07 indicates that the sensor should be replaced.