While driving in Mountain mode on the hwy, the engine stutters like its confused about whether to be in electric mode or engine/generator. There is plenty of battery range, 13 miles when I switch back to battery/normal mode. Now the check engine light is on. Most of the time the stuttering seems to happen while going down hill, but still occurs a bit either on a flat road or uphill. It seems to iron itself out after a while....for now. Engine light stays on though.

I've read people having issues with mountain mode but they turned it on with the battery depleted. This is not the case.