Q: Code p0306 indicates that Cylinder 6 had too many misfires within a predetermined period of time.

Hi there. When it comes to a misfire to a cylinder, there are many possibilities that can cause this to happen. First check to see if the spark plug is firing on cylinder 6. Then check the fuel injector and make sure that its working. If the spark plug and fuel injector is working, then you will need to perform a compression test on cylinder 6. The first puff should be half of the final puff. If the first puff is less than half, then the piston rings are not sealing properly. If you have a good compression reading, but its lower than the cylinders around it, then you will need to perform a leak down test to determine if the cylinder has a bent or burned valve or a blown head gasket. If everything checks out to be working properly and the cylinder is sealed up good, then there could be a blockage in the exhaust runner making the cylinder not function. If you need further assistance with your cylinder 6 misfiring on your engine, then seek out a professional, such as one from Your Mechanic, to help you.