Run the heater for at least 15–20 minutes once a month, even in summer, to prevent the fuel from "gelling" and to keep the burner clean.

Use the or Reverse (<) buttons to set the current time. Press the Clock button again to save. Programming a Preset Start Time:

To turn it off manually before the timer ends, press the Flame button again. Press and hold the Clock button until the time flashes.

If the display shows "F" followed by two digits (e.g., F01), this is a fault code. Refer to the Webasto 1533 Manual to identify the specific issue. Webasto Oval Timer 1533 Operating Instructions Manual

Press the repeatedly to choose the desired program number (1, 2, or 3).

If the heater fails to ignite, you may need to clear a "lockout." A common method is to remove the 20A heater fuse for 30 seconds while the unit is trying to start, then replace it.