Controller displays UF and generator shuts down or will not transfer load.

Safety first: Turn the system to OFF and disable automatic start. Allow the engine to cool before touching moving parts.

• Inspect governor linkage: With the engine off, move the throttle and governor linkage by hand. Ensure it moves freely and returns by spring tension. Clean any debris and lightly lubricate pivot points with a dry lubricant (avoid oil that attracts dirt).
• Check fuel supply and pressure: For NG/LP units, verify gas valves are fully open. Have a gas technician confirm inlet pressure at the generator gas valve meets Briggs & Stratton specifications under load.
• Clean air and fuel path: Replace a clogged air filter. If the engine surges or bogs under load, the carburetor main jet may be restricted. Remove the carburetor bowl and clean the jet with carburetor cleaner and compressed air.
• Ignition performance: Inspect spark plugs for fouling and correct gap. Replace if worn. If misfire persists under load, test and replace the ignition coil as needed.
• Clear the code: After corrections, cycle the controller to OFF then AUTO and test in MANUAL with and without load.