Boiler shows E007 and will not operate, often immediately at startup

Safety first: Turn off power and close water isolation valves before removing any sensors.

• Step 1 – Locate inlet sensor: Remove the front cover and find the inlet water temperature sensor on the cold water or return line entering the heat exchanger.
• Step 2 – Inspect connector: Disconnect and inspect the sensor plug for corrosion or moisture. Clean and dry as needed, then reconnect securely.
• Step 3 – Check wiring harness: Trace the harness to the PCB, ensuring there are no breaks or pinched sections. Repair any visible damage.
• Step 4 – Sensor replacement: If the error persists, replace the inlet thermistor. Shut off water, relieve pressure, remove the sensor, install the new one with proper sealing, and restore water and power.

If E007 remains after sensor replacement, further PCB diagnostics by a professional are required.