I recently purchased a 2000 ES300 and when I shut the engine off it knocks. Yesterday my wife drove up to me in the yard and I could hear a knocking in the engine, she didnt remember when it started. There is no CEL illuminated. Its probally the knock sensor or the harness??

 

If you're saying that you hear a knock after the engine is shut off, than its probably your hot exhaust metal cooling down, contracting, and making a ticking noise in the process.

That noise is normal. Many cars do it. Mine does it as well, and there is nothing wrong with my car.

Phil

 

Thats not it, the engine knocks when you turn the ignition off

 

Any chance you can potst a video or Audio of the event. It's hard to understand what's going on.

 

engine knockon or post detonation, is called 'run on', engines which do it are still turning. The ignition source is carbon build up on either the piston or head. It's very uncommon on a modern engine. Mostly because there is no fuel source to supply it, because the injectors are off, and so is the ecu. But it might manage a couple of revolutions, .. it might actually run in reverse for several turns.

 

Seconded.

If you could, give us some audio or video of the knocking. That would give us a better idea of what exactly your car is doing.

 

Does the engine idle high? Try this experiment to rule out 'run on',- next time you turn off the engine keep it in gear and see if the noise stops.