Answer: There are many possible causes of a knocking sound coming from your car engine. Some are higher priority than others, but it is important to be able to recognize what these knocks mean so that you can take the necessary precautions to keep your car in good shape. Some of the most common causes of a knocking sound in the engine include lifters or connecting rods, carbon buildup, timing chain out of sync, overheating engine, vacuum leaks, spark plugs, failing knock sensors, or fuel or octane quality. You may have low oil pressure, a low engine speed, or damaged pulleys and tensioners as well. If you are hearing a very faint knock sound every once in a while, rather than consistently, this may be a detonation knock. The car cylinders are where power is generated through fuel combustion. Detonation knocking sounds occur when the air fuel mixture in the cylinders is detonating at more than one place at once. Because there are so many different possible causes of an engine knocking noise, you should get your car checked out to try and narrow down the specific issue.