Greetings! I am getting an intermittent code 44 and am tracing the problem down. My MAF was bad so I replaced that, which made the car run better but still get the Code 44. Previously, I had a check valve go bad on the driver's side exhaust manifold and the hot exhaust gases backed up into the AIR hose and melted it. I have replaced the valve and hose but am wondering if more damage had been done. The GM manual says to check the system by squeezing the hose in front of the manifolds to see if the "block learn" values go down. I don't have a scan tool and don't even know what "block learn" values are. Is there an easy way to check to make sure that the AIR system is NOT pumping air into the exhaust manifolds during closed loop?