I worked on a 2003 5.3 taho Monday, the only code was bank 1 n2 lean the person had changed a lot of things trying to fix it. the only thing I could find was the data on my scanner never changed all the parimiters stayed the same. I haven't run into this before I cleared the codes and setting in the shop they didn't come back, but still no data change, I thought some one might have reflashed it ?