GE GFDS250EF Manual page 74

Service Mode Tests
(t1) Setting and Viewing Model Codes:
(3)
Pressing the Start key will temporarily save the User Interface Mode
Type.
Next the current Heater Type selection is displayed as "g" Gas or "E"
Electric.
Pressing Temp or Level key will alternate the 7-segment display
between the two Heater Type selections.
Pressing the key Start for 3-seconds will store the both the User
Interface mode and Heater Type into non-volatile memory.
If the sequence is interrupted the User Interface Mode and Heater Type
will not be saved.
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