Ranges fail in two distinct categories: cooktop problems (igniters, burners, surface elements) and oven problems (bake/broil elements, igniters, sensors, control boards). The diagnosis is almost always physically separate. Always disconnect power at the breaker before service, and shut off the gas valve on gas models.
Element open. Pull the rack and look at the element — if you can see a break, blister, or burn-through, replace it. If the element looks intact but doesn't heat, test resistance with a meter at the element terminals — should read 19 to 115 ohms depending on wattage. Infinite resistance means open. The control board could also be failing to send voltage; if you have 240V at the element terminals when bake is called, the element is the problem.
Same diagnosis as bake element but on the upper element. Many broilers cycle on and off rapidly during use — that's normal.
Igniter (sparking) or wet burner cap. Lift the cap and look — if the spark electrode is corroded or broken, replace it. If you smell gas without sparks, the igniter has failed. Soak food-clogged caps in hot soapy water and dry thoroughly.
Flame sensor (gas with sealed burners) or the cap is misaligned. Cycling on and off is the safety system shutting off because it can't sense flame.
Weak igniter — it's drawing enough current to glow but not enough to open the gas valve. Replace it; it's a common failure and the part is inexpensive.
Verify the oven temperature with an oven thermometer (calibration drifts over years), confirm the convection fan runs if your unit has one, check that the bake element heats evenly across its length, and clean off any spilled food on the element. Many ovens have a calibration adjustment in the user menu.
Door must be locked (latch motor or switch failure), control board, or thermal fuse from a previous run that ran too hot. Self-clean cycles are notorious for blowing the thermal fuse and main control board because they run the oven to over 900°F.
A scratch is cosmetic. A crack in the radiant glass is a safety issue and the cooktop must be replaced — replacement is expensive enough that on older ranges you should compare to a new unit.
Stripped knob or stripped valve stem. Knobs are cheap; valve replacement is more involved.
Generic mapping: F1 is usually a stuck key or control board; F2 is over-temperature or oven sensor; F3/F4 is an open or shorted oven temperature sensor (a $20 part); F9 is door latch. The service manual for your specific model is authoritative — values vary by manufacturer.
Gas line or gas valve issues should go to a licensed technician. Door seal replacement on self-cleaning ovens is technician territory — the seal must be installed perfectly to keep the cycle from venting hot air into the room.
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