Appliance Repair Revelation: Troubleshooting a Gas Oven That Won't Fire Up

If you have a gas oven that's not firing, don't be bonehead and automatically assume the valve is bad (hint: it's usually not). What else could it be? Ah, Grasshoppah, read and learn.


You may even see the orange "glow plug" (called a hot surface ignitor) glowing orange and so assume that it's OK. But you would probably be wrong. Many $$ wrong. You gotsta measure the current drawn by the ignitor before you can say it's OK or not. The gas valve has a bi-metal that snaps open when a certain amount of current flows through it to heat it up. The ignitor is wired in series with the gas valve. As the ignitor ages, its resistance increases to the point where not enough current is flowing to the gas valve bimetal to open it up. Consequently, the gas valve never opens up. BTW, a common symptom of the early stages of this problem is erratic temperature control in the oven due to delayed firing of the bake burner while cooking. This service sheet illustrates the main players in the ignition system and how to test them.



Here's another picture that shows the main components in a gas oven. The big thing to notice is the difference in current draw between the round and flat ignitors. Look, there's just no substitute for measuring the current draw--this is the gold standard for diagnosing gas oven ignition problems. I'll let you in a little secret, though: if the ignitor glows but the oven takes longer than three minutes to fire up then, 97.98745987% of the time, the problem is a bad ignitor. Here's another tip: if you buy the ignitor through this parts link and that doesn't fix it, you can return the ignitor for a refund. Who else but the Samurai will make you a deal like that?



I've talked to lots of shotgun parts-changers about this problem. These are guys who can't be bothered with the theory of operation. Besides, they already know everything anyway, so they just shoot from the hip and end up replacing a bunch of parts that were still good. They blew beaucoup bucks on a new valve and just can't understand why the oven still won't fire up. But now, you know why.