DIAGNOSIS The controller is detecting a fault in the startup sequence, most commonly a failed firepot ignition or a problem with the RTD temperature probe.
FIX Start with the ignition system. Open the grill, remove grates and drip tray, and vacuum out the firepot completely. Ensure there are no wet or broken pellets blocking it. After cleaning, try a restart.
IF THAT DIDN'T WORK The RTD probe might be faulty or disconnected. Unplug the grill, let it cool, and locate the probe (a thin metal rod) inside the cooking chamber on the left side. Check that its wire connector is firmly plugged into the back of the controller housing.
HEADS UP An 'err' code often recurs if the firepot isn't absolutely clean. A single pellet fragment or ash can prevent the hot rod from lighting the fuel.