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The code P0686 refers to the power supply relay. This relay controls many things and among them is the ignition coil module. I would first start by checking all fuses, including those that are mounted to the bottom of the relay panel under the dash. Fuse 29 in the fuse panel on the drivers side of the dash controls the ignition system power. There are also fuses in the ECM box located under the hood on the drivers side under the wipers. This is also where the power supply relay is located at, it should be marked with a 219 on the top of it. I hope this information has helped and if it has please click on the accept button as that is the only way I am compensated for my time and knowledge.
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