2011 Prius, 223,000 miles. Car shakes & rattles (probably rolls too!)when backing up or going forward from a stop. Check engine light is on, sometimes flashes when rattling. Vibration stops at about 20 mph or so. No indication of less mpg or overheating. Help! Tom
The flashing CEL and ‘rattleling’ means you have a major problem. It needs to go to a mechanic, preferably towed.
If you drive a car with a flashing check-engine light, you can cause expensive damage.
Given you car’s hybrid configuration, could be any number of problems. My guess – if OP will allow a guess – is the gasoline engine is misfiring due to unmetered air getting inside, due to a vacuum leak of some sort. That sort of leak will have less effect on performance the greater the engine’s rpm and load.