Arrived at location on 9/30/21 - Found convection oven off. Chef explained that it would intermittently not heat. Sometimes it would, sometimes not at all. Confirmed door switch works, burner track is clean, flame sensor is clean. Checked module, module gave 9 blinks, which is internal issue with module. Will need new ignition module. Returned to location on 10/6/21 - Arrived and customer was finished using it. Open and removed the faulty module and installed the new module. Power on and unit comes on and heats. Open / close doors and it restarts each time. Installed front panel and the burner cover and restarted the unit. At temp and has not failed. Back in service.