Have HVAC Questions? Ask an HVAC Expert for Answers
33 is an open limit code. Do you know what limits are and do you have a multi meter to troubleshoot?
Below are most likely causes .Lets start with checking the reseteable ones. Look above burners and on draft hood. They will have a button similar to one shown below that pushes in to reset.
Approaching 11PM here .Will be leaving office soon.First check the resetables. If all are closed , trace the limit circuit to locate each limit and check it for continuity until you find which one is open.