Boiler displays 102 and locks out, no heating or hot water

Safety: Isolate electrical power before removing the boiler front cover. Do not disturb gas components.

• Verify system pressure: Check the pressure gauge. If below 1.0 bar, top up via the filling loop to 1.2–1.5 bar and bleed radiators. If the gauge shows correct pressure but error 102 persists, suspect the sensor.
• Inspect pressure sensor: Locate the Ariston water pressure sensor on the hydraulic block. Check for leaks, corrosion, or damaged wiring. Reseat the electrical connector.
• Clean sensor port: With the system drained and power off, remove the sensor and check the port for sludge or limescale. Gently clean with a small brush and flush with clean water. Refit with a new O-ring if needed.
• Reset and test: Restore power, repressurise the system, and reset the boiler. If 102 reappears, the sensor is likely faulty and should be replaced.
• PCB check: If a new sensor does not resolve the issue, the main control board may be defective. This should be diagnosed and replaced only by a qualified engineer.