If you own a 4000 or 4010 Mule, and perhaps others that are of the 2cylinder type, there is an ignition -coil for each cylinder. When one of them dies, and they must because there seem to be a lot of them sold through the internet and that coil is used on several makes of engines, then your DFI light will not go out after the engine is started which indicates that you have a problem. If it's the coil then you are running on one cylinder and the power you now have is enough to get you back home, the limp home mode. The # 1 coil is the one in front and isn't bad to get to but the #2 coil is the one in the rear and next to impossible to get to. If you read the manual it tells you how many things you must take apart to get to it Trust me, You have a lot to disassemble, Tire, shock absorber, torque converter housing , clutch, starter motor, and then the coil. I figured out how to eliminate that but you need patience , a lot of swear words, a lot of luck, and a special 8 mm wrench.. Pray yours doesn't die and if so you may want to take it to a dealer and let them fix it. Gerry C