Display shows Er4 and grill shuts down or will not maintain temperature

Safety first: If there is any sign of active flame or grease fire, keep the lid closed, turn the grill OFF, unplug it, and use a fire extinguisher rated for grease fires if necessary. Do not use water.

• Allow full cool‑down: Leave the lid closed until the grill is completely cool to the touch. This may take 30–60 minutes.
• Clean grease and ash: Remove grates and drip tray. Scrape and clean all grease channels, the drip pan, and the grease bucket. Vacuum ash from the fire pot and bottom of the cook chamber.
• Inspect high‑limit sensor: Some Nexgrill pellet models use a separate high‑limit thermostat or thermal fuse near the fire pot or exhaust. Check for a tripped or damaged sensor (discolored, cracked, or melted). Replace if visibly damaged or if it tests open with a multimeter.
• Check pellet feed settings: Verify that you are using the correct pellet type and that the controller is not set to an unusually high feed rate or manual mode that could cause over‑fueling.
• Reset and test: After cleaning and inspection, plug the grill back in. Some models require a power cycle (unplug for 5 minutes) to clear Er4. Start on a low or smoke setting and monitor temperature closely for 20–30 minutes.
• Replace control board if overheat recurs without cause: If the grill overheats again despite proper cleaning and normal settings, the main control board temperature logic may be faulty and should be replaced with a Nexgrill OEM board.