Description:In US expecially in CA have regular smog checks.If your battery was disconnected days before your smog check, and you didn't use a device like this to save your ECU history, you won't pass smog until days or weeks of driving has rebuilt the data .OLLGEN ecu emergency power supply cable memory save to help you solve the embarrassing situation!This obd2 cigarette lighter cable will keep things from resetting to their factory state while replacing the battery or alternator and other repairs that require disconnecting the battery. Simply plug this into the OBDII Male port and connect it to a battery source.Note:It's car emergency cable, for replacement of car batteries ONLY; since the cable is specially made with anti-protection on incorrect POLARITY, so that the electric power can ONLY be transmitted from cigarette insert to auto, and can't be used as auto connector.Instruction:1. Make sure ignition is off and all lights and anything that draws power is off.2. Plug into OBD2 Male port of car that is to have battery disconnected making sure it is firmly seated.3. Shut the doors so any interior light and headlights go off.4. Attach alligator clips on battery of a different vehicle or spare battery. (Not the one being removed or the one being installed)5. Verify the red LED is lit on the cable. If it is not, check the polarity.6. Staying clear of the ECU cable, disconnect the battery terminals being careful the positive does not touch the ground of the car.7. Install new battery being certain not to open any doors or use the fob why on donor power.Package Include:1x OBD 2 Vehicle Emergency Power Supply Cable1x Alligator Clip-On 12V Car Battery Cigarette Lighter