GMC Jimmy P0440 AND P0442 Codes

My 2000 GMC Jimmy 2WD 4.3 L IS INTERMETENTLY SHOWING THE CODE P0440 AND P0442 EVERY OTHER WEEK. DO YOU HAVE A TRICK OR OTHER SOLUTION TO REPAIR AND FIND OUT WHERE THE SMALL LEAK IN THE EVAP SYSTEM? BECASUE GOING TO DEALER TO SMOKE TEST THE SYSTEM WAS SO EXPENSIVE. ANY SUGGESTION FROM YOUR EXPERTISE? THANKS IN ADVANCE

Well, your leak would be in the evap purge valve, the intake manifold, the hose connections, the hoses themselves, OR the evap cannister. Those are the commonalities of those two codes. So check all the connections and hoses for cracks. If you can’t find any, THE most common problem I see in those Jimmys is a bad evap purge valve if you want to take a good guess at the problem. Now if you want to pinpoint it down, you’re not going to have the equipment and experience to do it yourself (smoke machines cost a grand and upwards.) So in that case, find a good independant mechanic with a smoke machine. They should charge a lot less than the dealer. But, as I said, I do change out a lot of evap purge valves on that model.