One problem related to check engine light on has been reported for the 2014 Toyota Prius. The most recently reported issues are listed below.
I am the first owner of this vehicle it has about 110k miles recently the started to shake when I start it in the morning or when parked for a while it started to show the check engine light some time it goes away on its own so I figured I will do 100k service changed the spark plugs oil filter etc. The shaking went away but after 1k miles the symptom came back with service engine soon and check engine when I scan it the code read p0301 I have also noticed the coolant is low went Toyota picked up a coolant and added about a quart then the problem still persisted when I went online for an answer I was surprised by what I discovered most of the cars with the same problem needed an new or rebuild engine as long time Toyota fan owned many different ones I was baffled by this problem I need help. As I learned online this problem affects most of gen 3 Prius at this point I don't know what to do except ask Toyota for repair or replacement of the engine as I just finished paying for it. The problem happens only when the engine is running at stop or driven at low speed I have also notice the average gas milage suffurs. When the car is accelerating the problem seems be unnoticeable.