Unfathomable Bugs #7: The Broken Oven

posted by Craig Gidney on September 2, 2013

Today’s bug comes courtesy of General Electric. Thank you, General Electric, this series wouldn’t exist without the generous support of entities like you.

Software bugs have a tendency to create extremely confusing effects that are, in retrospect, due to a head-slappingly obvious mistake.

Contrast that with problems in the “real” world, which (in my limited experience; cpu designers and mechanics definitely disagree) usually result in a thing doing nothing instead of something and come down to a broken part.

An exception to that personal pattern was the oven at my apartment.


A couple years ago, I moved into an apartment with my then girlfriend. The apartment was nice but, before long, we realized something was wrong with the oven.

Sometimes the oven would work, but usually it would barely get hot enough. In addition to not being hot enough, it would sometimes burn things.


Psychic Debugging

Eventually we got fed up with the oven being unreliable, and I went to place a maintenance request. I was explaining to the land lady that the oven seemed to heat up too little but too much when she stopped me and explained what the problem was. She’d diagnosed it without even being in the same room.

(She’d probably seen it before.)

Yeah, the temperature and bake/broil knobs were reversed.

The oven wasn’t getting hot enough because when we set the oven to ‘bake’, we were actually selecting a relatively low temperature. The bottoms of things tended to burn anyways because when we set the temperature knob, and were actually setting the mode, we’d end up broiling things intended to be baked.

I went back to the apartment and switched the knobs. The oven worked fine after that.


Put labels on the oven instead of on the knobs. Design things so it’s impossible to accidentally mislead the user.

I’m not sure if this analogizes to software… maybe homograph attacks?

My Twitter: @CraigGidney

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