Appliance Repair Wisdom for the Ages

Sunday, September 19, 2004

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.

To learn more about your range/stove/oven, or to order parts, click here.

Samurai Appliance Repair Man cast these pearls at 01:45 ET.  [permalink]

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16 Comments:

This information was so very helpful. Our gas oven just stopped firing up one afternoon, and I had just used it that morning! I downloaded the Hot Surface Ignitors service sheet and we determined that the ignitor had to be replaced. I purchased the ignitor, installed it and now the oven works like a charm. We were able to avoid a costly visit from a repair service and we only spent $70 for the part.

Thank you!

By  Kim T., at March 15, 2005 12:04 PM  

What about the range ignitors? None of my gas burners will ignite unless I use a match ;-) Thanks.

By  Anonymous, at July 11, 2005 3:36 PM  

Are you referring to your stove burners? See this page.

By  Samurai Appliance Repair Man, at July 11, 2005 3:54 PM  

With the help of this site I was able to repair my sister's older Hotpoint gas range. Pretty easy diagnosis as the ignitor was not lighting at all. After ohming out the ignitor and getting an open reading and then checking for voltage at the ignitor and getting 120 volts I knew the ignitor was shot. However, accessing those two screws holding the igtinor in place were another matter. After two hours of feeling incompentent, I was able to get to them with a small socket fingertips only. My sister and I were very happy. Thanks for the help.


Jason

By  Anonymous, at October 01, 2005 8:48 AM  

Cool, thanks for the repair story!

In the future, when you run into something like that, be sure to come see us in the repair forum where we can get you diagrams and detailed repair procedures specific to your range.

By  Samurai Appliance Repair Man, at October 03, 2005 2:15 AM  

Uh, the link to the repair forum is here.

By  Samurai Appliance Repair Man, at October 06, 2005 8:17 PM  

I have a Tappan gas range/oven. The oven takes about 3-4 minutes to ignite during which time a strong odor of gas is present. Upon ignition, a bang occurs from the buildup of gas in the oven. Could this still be the ignitor? The broiler works fine suggesting the valve is ok.

By  Anonymous, at March 30, 2006 8:26 AM  

Could be the ignitor. Could be a bad valve. You awwta measure the current draw through the ignitor, as I painstakingly describe in the article, so that you'll know without having to guess.

By  Samurai Appliance Repair Man, at March 30, 2006 8:33 AM  

How about this variation of the problem? When I press the 'bake' button, the ignitor glows, but the oven never lights. However, if I use the 'preheat' button or the 'clean' button, it works like a charm. Thx.

By  Jerry, at April 01, 2006 1:04 PM  

Jerry, in your case, I'd measure both the voltage and the ignitor wire harness and the current draw through the ignitor in both bake and "pre-heat" modes.

By  Samurai Appliance Repair Man, at April 01, 2006 2:38 PM  

Much like Jerry's situation, gas-oven, bake function does not work. Ignitor glows, no smell of gas detected at all, and ignition does not click. Nothing. But broil works so gas is coming in. Ingitor has been replaced twice before, both times it failed gradually with intermittent baking heat, and a gas odor detected when it was failing. Is this the ignitor again even though there is no odor of gas? THANKS!

By  MD, at May 15, 2006 12:54 PM  

Have a question on our gas over...the bake function does not work (the igniter seems to glow, but the bar only spurts out a little gas then goes out - max temp is about 130F). The broil function works fine though. Any suggestions on what the problem may be?

Thanks!

By  G P, at August 02, 2006 4:37 PM  

Master, I am humbled by both your wisdom and generosity. Half of my gas GE Specra's burners have not been self igniting for many months. But I know how to use a match, so I lived with it. Yesterday, the oven stopped igniting. I came here this morning, read your clearly written troubleshooting instructions and 30 minutes later, everything, both oven and burners, work perfectly again. A crimped and frayed wire, now taped and suspended with a zip tie to keep it out of harm's way. Thank you. May your kindness and generosity return to you seven fold.

By  Thomas M., at August 05, 2006 3:23 PM  

Great advice! I was running around looking for a gas valve...and ignoring the igniter because, hey, it was glowing just fine. The current was supposed to be 3A, but it was less than 1A. Aha! $50 later, a working oven. Fantastic. I'm feeling clever, and there's a pie in the oven courtesy of the Mrs. Resistance seems to increase in failing igniters and therefore current decreases. Resistance (cold) was 300+ ohms. The new one had (cold) resistance of 100 ohms. The other igniter in the oven had a resistance of 120 ohms. In order to get a current of 3A through at 120V, it would have had to have a resistance of 40 ohms when hot. Does the material used in the construction really drop with increased temp? Unusual -- and a great safety feature. Wonder if cold resistance could be used to test these igniters if you don't have an amp meter.

By  Duran, at December 21, 2007 2:41 PM  

I have a GE XL44 gas oven/range. The ignitor went bad in the oven, and I just replaced it with a brand new one. The new one now glows, and opens the gas valves, but the burner still doesn't light. I can hear the gas passing through to the pilot, but when trying to light it, it just blew my lighter out. Do you have any suggestions, as a.) what I am doing wrong and b.) what to do??
Any help would be appreciated. Thanks
dxter

By  dxter, at December 24, 2007 10:33 PM  

Thanks a bunch for this website. This is just the latest among many quick, accurate and inexpensive fixes. My Ge XL44 range oven has a flat igniter and it was only reading 2.5 amps. A trip to the parts house and $38.00 later I was cooking with gas. As an added benifit it gave me an excuse (and permission from my wife) to buy that Fluke Current clamp I have wanted for a while. Happy troubleshooting. Love the comment about shotgunners, those who can't be bothered with theory of operation. I know lots of those guys at work.

By  rrclyoung, at April 09, 2008 10:42 AM  

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