Ok, I had an 0410 dtc come up on my '02 c5. If you get this code, see if you can hear the air injection pump running. Listen closely for a high pitch vacuum cleaner type sound coming from under the driver side headlight. The pump should only come on when the engine is cold started and should run for less than a minute and then turn off. Also you will want to disconnect the large vacuum hose where it junctions near the alternator. While the pump is running there should be a strong force of air coming out of the front secion of the disconnected hose, the other end will sound like exhaust. If you are not getting any airflow that means that the valve is not opening. This valve is vacuum operated. Vacuum is switched on or off by a vacuum solenoid located behind the passenger fender and is mounted to the fiberglass inner structure. Check first to see if there are any blown fuses in the box under the hood, if not then there is a good chance that the vacuum solenoid is jammed. This solenoid has a filter on one end but does not always prevent moisture and dirt from getting in and jamming it. If you are as crazy as I am you can disassemble the solenoid and clean it. It worked for me but it would be easier to buy one for 25-30 dollars at the dealer. To access the solenoid, remove the lower part of the passenger fender skirt behind the front wheel and remove the screws from the lower half of the fender. This should give you enough flexiblity to access the solenoid. This is definitly a lot cheaper than doing it the dealer way and they tend to charge you for everything you don't need. My 02 dodge ram need two 7 dollar vapor/emission hoses and they wanted to charge me $350 becuase they supposedly needed to reflash my ecm. I disconnected the battery to clear the code and replaced the hoses. $350....15 minutes....hmm....I think I'll open a shop. Anyway, I hope this was helpful.