My 2001 Blazer recently gave me the P0171 code. I had the injectors replace which was giving me other codes all went a way except the lean fuel code. The SES light stayed off for about two days after getting the injectors and plugs done. I was told by another mechanic that I had a small exhaut leak about 3 months before, but there was no codes nor SES light on. I looked for disconnected hoses, but found nothing. I also changed the MAF sensor, but that was the cause. Anyone have any suggestions?????

 

its possible you could have a vacuum leak down stream of your map sensor??