Start checking the car engine for identifying the real cause of the engine problem and car engine P0685 Code helps to identify the real problem of the car engine and once the engine’s problem is found, you need to fix the car engine properly. The automobile engineer must know the way of solution and process of solving the car engine. So, you must let the automobile engineer to fix the car engine. Some hand tools are necessary for solving the car engine’s problem. By checking the symptoms of the problem and engine, the problem of the car engine can be fixed.