I just finished replacing the HCV on my 2001 and I must say that it is harder than it looks. While fumbling with the clamps on the HCV I pulled up a "vacuum" line that wasn't one of the four that connect to the plenum! Within the length of the line, I could not find any thing to connect it to. The line was running underneath and perpendicular to the four vacuum lines on the plenum and extends about 9 inches past the center of the motor toword the passenger side of the car. Does anyone know what this is? The car is running fine, but my check engine light was already on because I need to change an O2 sensor.

Jeff

Not, sure, but I think I saw the same thing and was equally confused. I was checking for vacuum leaks due to a P0171/P0174 lean fuel trim error. I saw an unconnected hose (1/4") coming from nowhere, strapped to the crancase ventilation setup. I think that it might be a fuel regulator vent or something. It was not shown in the GM vacuum hose routing diagram or anywhere else in the manual.

Had the same problem, didn't get any help here so I went to the dealer, found out it is a vent hose for the transmission. The end of it just sits there maybe was strapped at one time. Hope this helps.

Had the same problem, didn't get any help here so I went to the dealer, found out it is a vent hose for the transmission. The end of it just sits there maybe was strapped at one time. Hope this helps.

Agree

Try to orient end so it points down or level at worst. You do not want to allow debris or any liquid (e.g., rainwater or leaks) to enter this line.