I have a 2011 850 Sportsman EXP EFI. I have been plagued by the check eng. light for some time now. It is very intermittent and I've read everything I can find about it on here. I've changed a MAF wire harness and injectors because I thought maybe they were bad. Here is an odd (to me) thing I have discovered. Started it up a while back and the light came on. While it was running I was sitting there contemplating whether to sell it or shoot it, I noticed I had left it in 4WD. Moved the switch to 2WD and the check eng light went out. I thought, it's just a coincidence. It's ran fine since then for over a month. Started it yesterday and the check eng light came on again. I thought, why not try it. Moved the 4WD selector switch through the positions and the light went out and it runs great. I had been riding a few days before and had used 4WD. This seems really odd to me. Has anyone else experienced this or maybe knows what this might be? Thanks.