2001 Saturn SL1, SOHC, 222,000 miles, getting a P0410 error code.

I found a loose vacuum hose to the top of the intake manifold. Here's a photo showing the hose location and the hose that was disconnected.


The rear-most hose is the hose that had become disconnected.

(I'm looking for a way to halve the size of the picture, but I can't find one.)

Can that hose disconnected at that highlighted cause P0410 errors?

 

That code is for the air injection system and I believe the small vacuum hose in front goes to the control valve for the injection system. So perhaps with the rear one disconnected there is enough of a vacuum loose to affect the control valve. Did you clear the code and see if it returns after connecting the hose?

 

Hook it up and clear the code. Does it come back?

 

With that many miles on it, the hose may have a split in it. Check both ends and trim it if you have enough slack, then reattach it.