1439   Error: Replace 3rd MFC assembly. The valve for NH3 in the Massflow assembly is not closing completely.

There is a gas leak from the 3rd MFC gas system. Switch to Standby mode, close 3rd Cell gas valve, and confirm the flow rate to make sure that gas is flowing at a rate of at least 0.35mL/min.

Check for leaks from the gas piping system. The following are the probable causes.

• Leak from the connection sections of the gas piping.
• Deterioration and damage of the gas pipe or hose.
• Faulty 3rd Mass Flow Controller module.