I just ran into this problem and was actually unable to get it off, after PB Buster, torque wrenches, everything.

I called Honda and they said that they don't evne use that, they just run water or coolant in the radiator one more time, cycle the car and then reflush.

In any case, yes it's the one just to the left of the heatshield.
see here.

http://spirit.netwiz.net/~antarius/other/failed/