My wife and I own a 2003 Denali XL and a 2001 GMC 3500 Duramax SLT crewcab. I've visited this site before to look up codes and simple fixes, but finaly created an account. Current issues: The Denali is running rough and throwing a p0446 code. I have it up on ramps right now, but I'm being lazy and waiting for it to warm up a bit outside before working on it. The truck once again has the p0089 code. The dealership replaced the fuel pressure module and regulator a few years ago under warranty. The injectors were done at 66k, 82k, and I did all 8 injectors at 108k. I have been replacing the fuel filters at every other oil change..15 to 16k miles but after the 2nd injector replacement, I dropped it down to 10k. Still the fuel system has issues. Very discouraging to say the least to go out and buy another GM. I had a 73 Blazer 20 years ago. I loved it. Easy to work on and I didn't have to smog it. I have no idea why I sold it.