L-jet Aux. air valve Bosch part # 0-280-140-101

What does it do?
Should I be able to just blow through it?
Any test spec.?

What problems will happen if it's pooched?

It works the same way as the rest. It should be open when cold--you should be able to blow through it. Actually, on the 1.8 version I think you should be able to see through it as well!! When the valve is warm, or when you hook up the electrical plug to +12V and ground for ~5-10 minutes, the disk inside the unit should turn and close off the hole from the one hose fitting to the next. At that point, you should not be able to blow through it--or see through it.

Think of it as a temperature-dependant way to bleed air from in front of the throttle to after the throttle. With a heater, to make sure that it closes after a while even when it doesn't get all that hot.

They can get frozen, usually in the open position. You may be able to disassemble and clean them, or simply cleaning them out and soaking them with your favorite penetrating oil may also work.

--DD