Dealer says I need a new throttle, $895.00

it's not, as far as i remember. not sure what part is the 'throttle' exactly. did the dealer charge you? if o, they owe you the codes
if you go for it, don't pay them until they take you for a drive

 

McGeorge Toyota will sell you a throttle body for $387 plus shipping.

2010-2018 Toyota Throttle Body 22030-37060 | McGeorge Toyota Parts


Assuming that's what they're talking about, it's a fairly easy swap, about an hour. You need to disconnect and reconnect a couple of coolant hoses.

I can post some info with torque values in a bit.

 

Watch @NutzAboutBolts video on intake manifold cleaning, pinned in the 3rd gen maintenance forum. In the process he removes the throttle body. In the attached are torque values for the throttle body hold down nuts/bolts (2 of each).

 

There is no single part that is designated " the throttle".
Some clarification is needed.

 

I'm thinking the TPS (throttle position sensor) may be out, or out of spec/adjustment.

 

Yeah, just "throttle" is too vague to know what part you'd need to get.

 

Yeah then it is the part linked in post #3. It is really not that hard to do. Watch the videos mentioned in post #4, to get a feel for what's involved. To get to it you need to remove the air box and snorkel, which is shown in the EGR pipe cleaning video. Removal of the throttle body is shown in the Intake Manifold cleaning video, IIRC.

You need a ratchet wrench, a 3" and 6" extension, 10 mm socket, long reach needle nose with bent tip, and a 1/4" torque wrench, probably with a 1/4" to 3/8" adapter (for the throttle body hold down bolts/nuts).

With your miles it would be good to replace the gasket too.

 

There ya go! That's specific. The Prius has some stuff that more primitive cars don't. But a throttle body is a throttle body. It's not that hard to replace, as @Mendel Leisk pointed out. Any car can be dangerous to work on if you're careless. Basically, stay away from the orange high voltage cables and the stuff they are connected to and it's no more dangerous than a gasser. There are Youtube videos for almost everything.

 

It simply may be gunked up from a lifetime use of dirty gas and air (air filters aren't even close to 100%). I had one begin sticking on a RAV4. A few minutes with throttle body cleaner and soft rags and it was working like new again.

Worse case scenario that it is indeed bad; find a good used throttle body and have an independent hybrid shop install it.

 

Yeah I'd be inclined to just dig down to it, give it a cleaning without even lifting it off it's base on the intake manifold. See @NutzAboutBolts video #14 here.

For a more thorough cleaning, remove the hold-down bolts/nuts, the electrical connector, and lift the throttle body off (leave coolant hoses attached), and clean from both sides. Alway apply carb cleaner to a cloth or q-tip, apply carefully. Torque value for those nuts/bolts is 7 foot/pounds (per the attachement in post #4). A 3/8" or 1/4" torque wrench is optimum for those values, preferably 1/4".

Look into the intake manifold while you've got the throttle body off the intake manifold too: I think you'll be taken aback by the gunk lurking in there. One of the bug-bears of 3rd gen is the Postive Crankcase Ventilation's propensity to dump sludge in the intake manifold.

At the least swab out what you can reach, and disconnect and pull off the Manfiold Absolute Pressure sensor (around 3 o'clock on the intake manifold, at the throttle body mounting base. Spray it with CRC MAF sensor cleaner, and gently brush with q-tip.

Something else you very likely need to be address, and may be a factor: with that amount of miles the Exhaust Gas Recirculation is likely well along in it's clogging. This involves the intake manifold as well. Some info:

The simplest way to see where you're at, is to check the degree of carbon build up in the EGR pipe, a stainless steel connecting pipe between the EGR valve and intake manifold. Watch @NutzAboutBolts video #16 here:

Nutz About Bolts Prius Maintenance Videos | PriusChat

Two or three other videos linked there too, for the full cleaning of the intake manifold, full EGR clean, and Oil Catch Can install.

Good thread:

EGR & Intake Manifold Clean Results | PriusChat

Another:

Oil Catch Can, Eliminate that knock! | PriusChat

Somewhat tools worth having:

E8 Torx socket (mandatory)
E6 Torx socket (optional, but good to have, to remove the throttle body studs from intake manifold)
3/8" ratchet wrench, regular and long handle, flex head, you can never have enough
1/4" ratchet wrench, or 3/8" to 1/4" reducer
Ratchet extensions: you can never have enough
Long needle nose piers, straight and bent tip
Ratcheting 12mm box wrench (optional, but makes disconnection of the EGR cooler from exhaust easier)
Torque wrench (3/8" and 1/4" both good to have)
Floor jack and safety stands (or ramps): basically some method to raise front, if you need to take underpanel off, which you may need to, both for access and to recover dropped items.

Some EGR info from the Repair Manual attached:

 

Whoever told you that "a prius is dangerous to work on if you don't know what you are doing" needs to have their 'listen to' privileges revoked by you, not because this wisdom is especially untrue, but because somebody is obviously using FUD to scare you.

ALL cars are dangerous to work on if "you don't know what you are doing." but that does not mean that you shouldn't be working on them for the very reason that ALL cars are dangerous to DRIVE if you don't know what you're doing.
The reason that ladders have more stickers on them than Subaru bumpers in Vermont is that manufacturers have to put them on because ladders are dangerous if you don't know what you're doing....and because their legal department and dot.US.gov requires them to do so.

So....
1.) If you wish to remain mechanically uninclined, it's gonna cost you.
I'd pay the dealer to swap out the TB and eat the $500, because putting miles on tow trucks is expensive too.....besides....there's a difference between a 'trusted' independent mechanic and a competent one. I think that they should have detected the TB trouble myself....so.....

B.) Start looking for another trusted mechanic.

III.) Based on my Prius ownership experience the hybrid (traction) battery should not be deteriorated by a 3-4 week slumber, presuming whomever fixes this problem thoroughly op-tests the car following the repair.


Four.) If you do NOT wish to remain mechanically uninclined, it's also gonna cost you, but not nearly as much as you think, and 'uninformed' might be more descriptive. One of the really groovy things about living the 2020 life is that you effectively have access to much of the sum total of human knowledge in your hands every day.
With a little bit of time and effort, you can be a MUCH more informed and effective consumer of automotive maintenance and repair (they ARE two different things!)
With a little bit of time and effort and $100 worth of Harbor Freight tools you can DIY nearly everything needed to keep your car or truck on the road for it's normal service life.


or?
You can continue to look at automotive maintenance and repair as a regrettable inconvenience and let others decide when, where, and how your car is serviced.

There are advantages to each approach.
Life is short, and some people simply do not want to be 'bothered' with car upkeep.
Time or money.....

Me?
I don't have a choice.

YMMV.....
Good Luck!!

 

Unless they cleaned it, it’ll stick again. Actually my first thought was that it just needed to be cleaned. But I assumed (oops!!) that if the dealer said it needed to be replaced that they had already tried cleaning or that they saw something broken. I recommend a can or two of TB cleaner and maybe use some MAF sensor cleaner while you’re in there. These should be YouTube videos to help you out.

 

I have a spare TB with low miles that I took off my car.