Diagnosis
Dirty or misaligned temperature probe (RTD), or excessive ash buildup in the firepot disrupting combustion.
How to Fix It
Clean the RTD probe and the firepot thoroughly.
- Let grill cool, unplug. Remove grates, heat baffle, and drip tray.
- Locate the thin metal RTD probe on the left interior wall. Scrape it clean with a grill brush or carefully use a damp cloth on a cool probe.
- Remove the firepot access plate. Vacuum out ALL ash from the firepot and the surrounding chamber.
- Ensure the heat baffle is correctly seated, not blocking the probe. Reassemble and do a test run.
If That Didn't Work
Check the door seal. A worn or leaky gasket lets out too much heat, causing the controller to overfeed pellets. Feel for hot air leaking around the lid during a cook. If significant, the gasket may need replacement.
Heads Up
Large temperature swings are normal for the first 10-15 minutes of startup as the grill stabilizes. Only worry if the swings are persistent and extreme after that period.