Bryant furnace-- code 34?

Good Morning:
About two weeks ago, we woke up to pilot lights on both the hot water heater and furnace out. No problem with restarting either on the first try.
This morning, the Bryant furnace was out (Model 373L--it and the house are 4 years old) -- I attempted to restart it, but get a Code 34 returned ("Ignition Proving Failure") each time, which then goes into lockout (Code 14). I wiggled each and every wire, cleaned the filters, and said a small prayer; however, no go.
Some poking around online brings up various suggestions; one more than most-- "oxide buildup on flame sensor". I am not a HVAC-type guy, and cannot locate the flame sensor... cleaning it with some steel wool seems to be my next option, if someone can point me to it?
Any other suggestions are most welcomed (prior to the dreaded service call)..
-cerealtrader
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see: http://www.arnoldservice.com/furnace_flame_sensors.htm
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bryant manual at: http://www.bryant.com/apps/finddocs/form.jsp?b=b
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It's likely to be right in front of, or right over, where the flame is supposed to be.
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