2016 Prius wont accelerate when stopped

Can you describe symptoms? Would the engine rev? Did it drop out of gear? Anything on the dashboard unusual? Had you been driving far? Would it move at all? Would it select reverse (and move backwards)? etc

 

Welcome to Prius Chat .

Some additional questions:

• How many miles on your Prius?
• Were there any dash lights that displayed?
• Did you press hard on the brakes and activate the hill start assist?
• How long have you noticed this?

Keep us posted .

 

As far as I can tell (it's been discussed before), hill start assist isn't activated by a "Hard Press on the Brakes" on Gen 4.

 

See this thread about Toyota service bulletin T-SB-0241-17, “Reduced Power When Accelerating From a Stop,” that describes a software update to the Hybrid Vehicle Control ECU (computer) for a similar problem:

TSB (NiMH only): Reduced power when accelerating from a stop | PriusChat

If this update hasn’t already been done, I’d ask the dealer to do it. Since the car is under warranty, Toyota should pay for this labor. I shared some other advice about a similar problem in post #6 of this thread:

Intermittently Doesn't Start from Stop | PriusChat

and more about vehicle control history events in post #9 of this thread:

A couple of things I have noticed | PriusChat

As others have noted, a description of exactly what’s happening might suggest other possibilities. For example, when the car has “not accelerated,” do you mean (1) there was no forward power at all, not even creep, with the brakes released; (2) there was no response to pressing the accelerator pedal, or (3) there was accelerator response, but less than you expected? Also, did you do anything, other than wait, to get the car moving again?

 

Good morning,

Apparently my current car seems to have a very unique problem, one that also happened identically with the 2016 Prius I had. The problem that occurs is; I pull into a downhill driveway, park get out of the car & normally return within 20 minutes or so, I then back-out of the driveway, put the car in drive, step on the accelerator & there is NO power to accelerate, no indicators on the dash, a 3/4 to full battery, but NO acceleration. I have to turn the car off, turn back on, put in drive, then it will go, However, it does the exact same thing at the next 2 stop signs, I stop, I put my foot on the accelerator pedal & there is NO acceleration. I have to turn the car off & on again, once I reach the freeway the car runs but I can tell not at 100% efficiency. My 2016 Prius did the identical thing 4 times, every time I took the car to the dealership & there was NEVER any error codes that came up. The last time that car malfunctioned, I had the car towed to the dealership & traded it in. I thought my problems were gone, but 2 weeks ago my 2017 Prius did the same thing. I just came back from the dealership & again they cannot find any problems & cannot recreate the issue. The issue started at around 22K miles with the 2016 & my 2017 has 24K miles, so similar mileage. The driveway that this has happened at is located at an elevation of 4500 ' ,the driveway is paved, a downhill slope, curved to the right & only about 30' from the street where I park & I go there 2-3 times a week, but on 4 occasions this issue has happened with 2 different cars??? The 1st time the issue occurred with the 2016 car, I was stopped at a signal to turn left onto the freeway, so it was on the flat, that time was a bit more traumatic with a line of cars behind me honking & it took awhile before I thought to turn the car off & restart before I got it running again.
The dealership is telling me I am on my own, I will be getting a dash cam, but that won't show much other that my reaction when it happens. I am concerned this will happen & put me in danger of loss of acceleration as I need to pull out into traffic or getting stranded with by issue & I am at my wits end & looking for some input or ideas ???

 

Check out this thread. There was another earlier as well.

2016 Prius wont accelerate when stopped | PriusChat

 

Welcome to Prius Chat @C. Reed sorry to learn of your problem, but I looked back into previous reports and found some advice from one of our esteemed contributors and quote his advice from then, below.

As he has already replied to your post (above) I shall leave you the rest to you and hope you can quickly resolve the problem. One further thought, did the same dealer supply both of your Prii (plural form of Prius)?

 

This post was some time ago but I'm having the same issue with my 2016 Prius not accelerating from a full stop at a light or even after just slowing down for a speed bump. I'm wondering if your car issue was resolved-
I took mine into the dealership for a full diagnostic almost a year ago for the same issue and they were unable to find anything. They were kind enough to waive the $150 diagnostic fee for me last year but I'm a full time student and hesitant to pay that much when I fear they won't be able to replicate the issue and will again tell me all is well.
As you mentioned, it's quite dangerous to be in traffic and suddenly unable to accelerate. Apologies if you did post an update regarding your issues in 2018- I just joined Prius Chat so that I could write you since I've been unsuccessful in finding answers elsewhere. In the off chance that you receive this, I'd be very appreciative for any advice given your experience. Thanks!

 

There are legitimate reasons why power is reduced or removed altogether when trying to accelerate. If a moving object (i.e. a car in front) is detected very close to your car then power is vastly reduced (a message is displayed on the MFD). If the car is in P or N it won't accelerate at all. If you are pressing the Brake pedal and Accelerator the car won't accelerate (or power is vastly reduced) too. If a stationary object is detected (this might include a high speed bump) then the automatic emergency braking will kick in keep the brakes activated. In most of these scenarios there is some kind of beep, warning, or message displayed.

 

I guess there are people who use the left foot for braking. They might still be braking with the left foot while accelerating with the right foot, causing the safety feature to trigger.

 

Just a thought: is the occurrence related to the fuel tank being (almost) empty? E.g. when you back-out of the driveway, this is in EV mode while the car needs the ICE to deliver sufficient power when you accelerate in D (and does not have fuel pressure yet).
(Other thought: 'vapor lock')
Has the issue been resolved meanwhile?