P0300 2002 Nissan Altima Sedan -

Question

Vehicle runs fine and Idles fine. It is running real good and once in a while the Check engine light flashes and when I scan it, it gives me a P0300 code. I checked wirings on injectors, coils and spark plugs and looks like new. I had an exhaust leak and had it repair. Only one time the engine was shaking and it went away. After that, no more shaking but Check engine light Flashes even when the engine is running fine and I scanned again and the P0300 still there even when the Check engine light is off.

Answer 1

Unfortunately there are many thing that can cause that problem. Faulty injector, coil or spark plugs can cause that problem. Even if the coils, injectors and spark plugs look OK, internal problem could cause an intermittent problem. I suggest performing a compression test, you could have a blown head gasket. If the cylinder compressions are OK, you could try run fuel additives to clean the injectors.