When the cel P0171 came on I took it to the shop, they cleaned the MAF sensos they cleared the codes drove it and the CEL came back on with P0171code then they replaced the MAF cleaded the codes drove it CEL back on. The car runs great no problems. Shop says its probably not the o2 sensor. Any one have any idea's on what keeps causing the CEL to come on with P0171 code?? HELP!