Controller displays ERR3 and grill will not start or shuts down shortly after startup

Safety first: If there is an active fire or heavy smoke, keep the lid closed, unplug the grill, and use a fire extinguisher rated for grease fires if necessary. Do not use water on a grease fire.

• Allow full cool-down: Leave the lid closed and allow the grill to cool completely. Do not restart until all internal metal surfaces are cool to the touch.
• Inspect firepot and burn area: Remove grates and diffuser plate. Check the firepot for excessive pellet buildup or clinkers. Vacuum out ash and pellets with a metal-safe ash vacuum.
• Check for grease accumulation: Inspect the drip tray, diffuser, and bottom of the cook chamber for heavy grease buildup that could have ignited. Scrape and clean thoroughly.
• Verify RTD probe position: Ensure the RTD probe is intact and not bent into the direct flame path. Replace if the probe sheath is warped, cracked, or heavily discolored from direct flame.
• Fan operation: With the grill reassembled and cool, power on and start a cook cycle while observing the combustion fan. Confirm it runs smoothly and provides strong airflow. Replace the combustion fan if it does not run or is weak.
• Reset and test: Clear the error by cycling power after cleaning and inspection. If ERR3 recurs without obvious cause, the controller's high-temp circuit or RTD may be faulty and should be evaluated or replaced.