Goodman furnace is showing single blink every 2 seconds. I see that a possible problem is the FLAME SENSOR. My main question: Is the flame sensor the SAME part as the ceramic ignitor ? If different, where is it in relation to the ignitor ?

No! Don't touch the ignitor if you don't have to. The flame sensor is usually at the opposite end of the burner arrangement from the ignitor, looks like a steel rod with a ceramic insulator and a single wire connected to it. Oxidation build-up insulates the rod causing poor flame current. Remove and clean it with fine sandpaper or steel wool, post back with results.

... found the flame sensor, no visual residue, sanded and reinstalled... negative results.
I believe that my problem is now compounded in the manner that initially the furnace would fire then shut down before reaching desired room temp... power off, power on and the cycle would do the same thing... now the ignitor lights, but the gas valve does not deliver gas. The ignitor will cycle 3 separate times then shut itself down.
Anyway, off to the parts store in the morning... probably going to try the flame sensor first, then the gas valve as Plan B.

Whoa, not so fast... if the ignitor glows but you get no gas, you may have a tripped/open flame roll-out switch. These are usually on a string of purple wires and surround the burner assembly. Check 'em. Also, I have encountered faulty pressure switches that will pass enough voltage to fool the circuit board, but won't support the load of the gas control, and (this is the best part), after the ignition trials you get an ignition fault code. Swell!

I have a York furnace and I know the sensor needs to be cleaned, but I can't find it!!

We had a guy come out last year and he chuckled and fixed it. I wasn't here to see where it was. Help!

KC13, you must really know your stuff.
Before leaving for the "store", found the (4) limit switches surronding the control box. The top one needed reset... lo and behold, the ignitor energized and the gas valve kicked in.

Unfortunately, this story is to have a not so pretty ending. The top limit switch continued to trip, off to the store for a limit and flame sensor. Installed flame sensor, the limit still trips. Upon further review, I am looking at the 4 burners with flame. All 4 look like the stream you would see coming from a fire hose... straight and dense. When the blower motor kicks in, the flame from burner #2 dances all over the place... thus heating the chamber and tripping the limit.

Ouch... the heat exchanger... correct??

... gonna have to bite the bullet on replacing a 8 y/o Goodman... just don't have the time to go through the paperwork... others told me that it would not be worth it anyway.
... There's a warranty on the exchanger, but as it is, my installer has since left this good ol' earth. I don't think I will replace it with another Goodman, although I realize it could have happened to any mfgr.
Thanks to all on the board who tried to help, and once again; thanks KC11.

I have changed many a failed Goodman heat exchanger, and they really aren't that difficult. If the unit is still in warranty, you might consider having it repaired as opposed to replacing it now. Even out-of-warranty, it is not an expensive part. I don't know what size your furnace is, but I recently replaced the primary out-of-warranty on a -075, it was about $90.