Rattling

Have you popped the hood and listened during startup? One time after a dealership visit they closed the hood without the hood support latch properly clipped, sounded bad, on ours. As an example.

 

Welcome to Prius Chat .

In addition to @Mendel Leisk ’s suggestion (which I had happen too), I’d pop the hood and see if anything else is loose.

Some questions:

• How many miles on your Prius?
• How long have you owned your Prius?
• Has this just become a recent phenomenon?
• Any recent work or damage to the car?
• Where in the great US of A are you located?

Good luck and keep us posted .

 

Clogged egr circuit

 

How much oil does it consume and in what mileage does it consume a quart?

Has it ever ran low on oil where the level couldn’t be seen in the dipstick?

Does your Prius consume oil?

Did the mechanic recommend the spark plug replacement?

Good luck and keep us posted .

 

You might qualify for piston and ring replacement under the excessive oil consumption Technical Service Bulletin. I believe the threshold is around one quart in 1200 miles.

I'll post the TSB's tomorrow morning. They essentially give you 2015 model year pistons and rings. And I would think do some cylinder and head clean up. A gasket kit rebuild is part of it too, including new head gasket I think.

Addendum:

Here's those TSB's. Dealeships should be aware of them, but it doesn't hurt to read through them, see what the oil consumption criteria are, and what's involved in the repair. It's pretty much a complete engine tear down, at least what's required to get the pistons out.

Note: with the oil consumption test, they top up the oil, put seals on everything, then tell you to come back in "1100 to 1300" miles, for the consumption check. I would definitely make the return visit as close to 1300 as possible, and do some spirited high-speed driving on the way there. Maybe a hill climb or two...