Hi, I have had a friend come to me with a 285kw VY clubby which has been running fine until the other day. His check engine light came on,after checking for codes I retrieved P0171 bank1 lean, P0174 bank2 lean, plus all his ltft's were at 23.5% for both banks. I cleared the codes for him and reset his trims so we could check it again a bit later. He informed me that by the next day the check engine light was on again. As a quick fix until we had time to investigate I just reflashed another standard 285 HSV tune into it to see if the problem went away. No such luck, has anybody got any ideas what or where to look for this problem or has anybody else experianced this type of behaviour before?