06 GTO engine codes, safety mode
 

I have an 06 GTO, 75,000 miles. I've had it for 4 months, and have had a few problems with it. Already had to replace the water pump and the alternator. Now after driving it for about a month with no problems, I took it on a drive about 120 miles. 3/4 of the way there, the car went into safety mode, and starting running really rough. I had the codes checked at Autozone, and they are p0449, p1516, and p2101. I let the car sit for a few hours, and it started just fine. But every once in a while, and getting more frequent, the car will go into safety mode immediately after starting, if it allows it to start at all. What could be causing this? The car is completely stock.

did you look up the codes, do you know what they mean??