Gas oven won’t heat, yet the top burners work
Usually: Over the years the oven’s glow-bar igniter loses strength. It can still glow orange while drawing too little current to open the oven safety valve, so ignition comes late or not at all.
What we do: We measure the igniter’s current draw instead of judging by the glow, check the valve, and fit a new igniter from the truck when that is the fault.