Display shows E4 and the smoker may shut down or refuse to start, often after extended high-temperature use.

Safety first: Disconnect power and allow the smoker to cool completely. Do not bypass safety thermostats for testing.

Steps to address E4:

• Check airflow and ventilation: Ensure the exhaust vent is open and not blocked by foil, grease, or debris. Confirm that the smoker is not placed in an enclosed space that traps heat.
• Locate the high-limit thermostat: Typically mounted on the outer wall near the heating element, it is a small round or rectangular device with two terminals.
• Inspect wiring and terminals: Look for discoloration, melting, or loose connections. Clean and tighten as needed, replacing any burnt connectors.
• Test continuity: With the smoker unplugged, remove one wire from the high-limit thermostat and test across the two terminals. A good normally-closed thermostat should show continuity at room temperature. If it is open and does not reset after cooling, replace it.
• Resettable types: Some high-limit devices have a small reset button. If present, press firmly until you feel a click, then re-test operation.
• Reassemble and test: Reconnect wiring, secure the thermostat to the cabinet, reinstall panels, and test at a moderate temperature setting.

Important: If the high-limit repeatedly trips, investigate for underlying causes such as a stuck heating relay, blocked vents, or incorrect temperature sensor readings. Persistent issues may require control board replacement.