Engine Knocking

I have a 2010 Toyota Prius. The other day I was stuck in a traffic jam - under 5 mph for at least 30 minutes…my engine started knocking/vibrating…once out of the jam, it felt like the engine was “missing”…I took it to the Toyota dealer in town and they changed the sparkplugs and cleaned the area…the car runs a little better but I was in a funeral procession yesterday and after about 15 minutes the car was knocking again. Any idea on what the problem could be? The mileage on the car is 125,000 (I drive a lot!)

Is there any knocking when the gas engine is not running, yet you’re driving on battery ?

Have you checked your oil level, has the oil pressure come on? A coworkers 2010 Prius started to consume oil around the 120k mark. He had no issues with oil consumption beforehand and had gotten out of the habit of checking the oil and was down 3 - 3.5 quarts when the engine started to knock. This occurred over the course of one oil change.

The dealer had to remove or replace the intake manifold because the some passages in manifold were clogged. Possibly due to the oil that was getting past the rings. The service was done under the emissions warranty.

Ed B.

The Prius ICE also has some sort of design issue. If you start the Prius, move it a few feet and shut it off OR you shut off the engine while the ICE does the “startup” routine…the next time it is started, it will most likely create a knocking sound for a few seconds.

Since you said you did not have the knocking issue before, it is probably a different issue.