I got this from OBDII codes .com
There is a technical service bulletin (TSB) regarding this code for a number of GM models. The TSB calls for the replacement of the AIR pump and the installation of a new secondary injection hose.
Additionally, if you simply replace the AIR pump the problem may return again (and again). If you replace the pump, also clean out the hoses and replace the one-way check valve. If this is on a GM model that the TSB applies to. In a few cases, people have put a small hole in the rubber cover on the pump which allows any water to drain out.
Replace the AIR pump AND one-way check valve
Test and clean the AIR pump AND test and replace the one-way air check valve
Replace the AIR pump inlet hose
Replace the AIR pump fuse (found under the hood)