really awful
Crashes / Fires:
2 / 0
Injuries / Deaths:
0 / 0
Average Mileage:
22,687 miles

About These NHTSA Complaints:

This data is from the NHTSA — the US gov't agency tasked with vehicle safety. Complaints are spread across multiple & redundant categories, & are not organized by problem.

So how do you find out what problems are occurring? For this NHTSA complaint data, the only way is to read through the comments below. Any duplicates or errors? It's not us.

2011 Toyota Prius engine problems

engine problem

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2011 Toyota Prius Owner Comments

problem #15

Apr 292016


  • 75,000 miles


Every once in a while - it can be months between events - our Prius momentarily slams on the brakes when driving at highway speeds while nothing else is going on. We know it's not operator error. It's happened to my wife several times and me once. When it happened to me I was driving straight ahead on a dry, lightly traveled divided highway during the day. Everything on the dashboard lights up, alarms go off, the car decelerates like I suddenly stomped on the brake pedal though my foot never moved off of the gas, it lasts for maybe a second and then the car is back to normal. It's the same each time it's happened. Luckily each time this has happened we haven't had anyone tailgating us. We've taken it to the dealer multiple times. The first couple of times they looked at us like we were loony. They checked it out and we got it back with a message that said the technician checked the computer and test drove it for 20 miles and the car was operating as designed. Except it happened again. We finally convinced them that this was maybe a legitimate issue and they said they brought in a Toyota field specialist who checked the car out and they said that the issue was the pcs wave radar sensor that was slightly out of alignment due to body damage (my wife had hit a small deer about a year prior to that - damage was minor and repaired at a local body shop). After they realigned the sensor, the car behaved itself for about five months. Until yesterday when it happened again.

- Woodstock, MD, USA

problem #14

Sep 142015


  • 21,000 miles
The contact owns a 2011 Toyota Prius. While attempting to park, the driver depressed the brake pedal and suddenly the vehicle accelerated forward and crashed into a pole. During the crash, the front end sustained significant damage. The air bags did not deploy. No injuries were reported and a police report was filed. The vehicle was destroyed. The manufacturer was not notified of the failure. The failure mileage was 21,000.

- Walnut Creek, CA, USA

problem #13

Apr 182015


  • 19,000 miles
The contact owns a 2011 Toyota Prius. While attempting to park the vehicle into a space at approximately 3 mph, the vehicle suddenly accelerated on its own. The vehicle traveled into a semi circle and struck a parked vehicle. There were no warning indicators illuminated. The vehicle was turned off. The vehicle was driven to the dealer, but no diagnostic was performed. The manufacturer was notified of the failure. The approximate failure mileage was 19,000.

- Kerrville, TX, USA

problem #12

Oct 012014


  • 93,081 miles


The contact owns a 2011 Toyota Prius. While driving at 5 mph, a 90 degree left turn was made and the vehicle accelerated at high speed and jumped the curb. The dealer was unable to duplicate the failure. The vehicle was repaired. The manufacturer was notified of the failure. The approximate failure mileage was 93,081.

- Clintonville, WI, USA

problem #11

Aug 082014

Prius 4-cyl

  • 34,000 miles
The contact owns a 2011 Toyota Prius. The contact stated that while attempting to park at 3 mph, the vehicle accelerated independently and crashed into a parking bumper. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure. The approximate failure mileage was 34,000. Updated 11/17/2014 updated 4/29/2015

- Sarasota, FL, USA

problem #10

Jan 042012

Prius 4-cyl

  • Automatic transmission
  • 5 miles
The contact owns a 2011 Toyota Prius. The contact stated that while driving 20 mph approaching a stop sign, the vehicle accelerated independently without warning. The vehicle was not diagnosed or repaired. The manufacturer was made aware of the failure. The failure mileage was 5 and the current mileage was 15,000. Updated 8/11/14

- Silver Spring, MD, USA

problem #9

Apr 222011

Prius 4-cyl

  • 2,156 miles


First incident: Was traveling approx. 68 mph on 405 freeway in los angeles (downhill into the san fernando valley). Dry conditions. Attempted to stop as cars ahead of me began to slow/halt and car lurched forward, carrying me to almost hit the car ahead of me, stopping only inches behind. Dealership could not replicate and dismissed my concerns. Multiple similar incidents all in good weather have occurred. Most recently on surface road with uneven pavement, traveling at less than 15 mph. Braking for stopped vehicles ahead, resulted in car lurching ahead.

- Diamond Bar, CA, USA

problem #8

Jan 142012

Prius 4-cyl

  • 100 miles
Periodically, after going over a bump at fairly low speeds, the car will accelerate. In light of the other unintended acceleration issue reported under ODI 10499911, I wonder if these two events are related -- possibly something to do with going from the motor to the battery?

- Falls Church, VA, USA

problem #7

Jan 242013

Prius 4-cyl

  • 8,200 miles
First incident: Was traveling approx. 15 mph on side street. Icy conditions. Attempted to stop at stop sign and car lurched forward, carrying me through intersection. Dealership could not replicate and thought mat might not have been fully seated. Toyota case # [xxx] 2nd and third incidences one month later (both on 2/23/2013) in fine weather conditions. 25 mph. Attempted to stop at stop sign and car lurched forward. Toyota case # [xxx] information redacted pursuant to the Freedom Of Information Act (FOIA), 5 U.S.C. 552(B)(6)..... updated 03/08/13

- Falls Church, VA, USA

problem #6

Jan 062013

Prius 4-cyl

  • 20,000 miles
2011 Prius, usa equipment package five. 20000 miles driven -- recommended service done every 5000, including the 20000 service done less than 1000 miles ago. Eastbound on I-78, a few exits West of allentown pa. Speed limit 65, radar cruise set to 68 and default three-bars [max distance]. all was good for 30 or so miles of rolling hills and light traffic. Then, with no change in traffic density or average traffic speed, the Prius started slowing down -- as would be quite appropriate if the driver ahead of me had eased up on the gas. 60, 55, 50, 45. Not quickly -- no where near as quickly as if I were to turn off the cruise. It was as though there was traffic slowing down ahead and the radar was just responding to it. But the traffic ahead was not slowing down. No beeps, no brake assist -- the Prius just gently slowed down -- in fact, the 'car ahead' icon was still displayed on the cruise indicator -- but in reality, the car ahead was far beyond where 'car ahead' should have been displayed. He was still doing 65 while I was down to 45. I was watching ahead and behind me -- still wondering if the radar had seen something I was missing -- and didn't really resume active control till cars behind started to get close [I really was concerned the Prius saw something I didn't!]. as the cars behind got closer, I just pushed down on the gas -- never de-activated the cruise -- and when back at 60 or so, the cruise again started to act 'normally'. there were no codes recorded, so I don't expect the dealer to even want to look at it. Toyota has not responded on this issue so far [other than to send spam advertising email].

- Bethlehem, PA, USA

problem #5

Jun 102012

Prius 4-cyl

  • 15,100 miles


We've been having a problem with the drcc (dynamic radar cruse control) on our 2011 Prius. The drcc locks up (freezes) -locking onto a phantom vehicle ahead and activating the beeper/applying the brakes - even when there is no vehicle is ahead! this creates a safety hazard as the car suddenly decelerates at interstate speeds with no warning to vehicles behind. We have had 7 occurrences of this problem. A search of the htsa database yields two similar reports (10448415 & 10421208). In all cases this has occurred on clear sunny days as the car was passing a semi tractor-trailer on an interstate highway when our car was passing the semi's cab. In most cases, there was no vehicle in front (car in constant speed mode) - it just suddenly acted like there was one! whenever this occurs, the car keeps braking and the only immediate solution is to turn disengage the cruse control. When the temperature is high (above 90 degrees) when we re-engage the drcc, the unit is still locked up! what cleared the locked up condition was turning off the car. On one occasion, when the ambient temperature had dropped below 90 degrees the drcc cleared itself. I have a log of all 7 occurrences of this problem. I have contacted Toyota about this problem (case #S [xxx] & [xxx]) and they had me take the car to my local Toyota dealer who used their techscan tool to download any system generated error codes - they found none. (of course, if the software design of the system does not recognize that malfunction has occurred, no error code will be generated.) the dealer also took the car out on a couple of (short) test drives, but the system performed normally. *note: A possible problem here is that, when hot, the radar unit is picking up signals from the truck's satellite position reporting system. There are several electronic manufacturing faults that could lead to this. Information redacted pursuant to the Freedom Of Information Act (FOIA), 5 U.S.C. 552(B)(6).

- Fairport, NY, USA

problem #4

Mar 082011


  • 28,600 miles
The contact owns a 2011 Toyota Prius. The contact stated that the vehicle accelerated unexpectedly after the brakes and start button were depressed intermittently. The vehicle was taken to the dealer. The manufacturer was not contacted. The vehicle was not repaired. The failure and current mileages were 28,600.

- Palm Dale, CA, USA

problem #3

Apr 142012

Prius 4-cyl

  • 7,200 miles
Drove over a speed hump, and as the front tires hit the level pavement, the car lurched forward. Responded to brakes just fine. Happened again a week later as both front tires simultaneously went over an edge dropoff at a construction area.

- Arlington, VA, USA

problem #2

Dec 022011

Prius 4-cyl

  • 15,956 miles
The car suddenly decelerated from 65 miles an hour to about 5 miles per hour while driving on a highway at night with the shoulder blocked due to road construction. This same problem was present in the 2004 Prius and was apparently the subject of NHTSA investigation. There was a recall issued on November 30, 2010 for 650,000 units of the 2010 Prius. Toyota has not been able to determine the cause of this problem in the earlier models and admits it doesn't know the cause of the problem in the 2011 Prius. This defect presents a great danger, especially when driving in heavy traffic at highway speeds.

- Victoria, TX, USA

problem #1

Feb 012011


  • 900 miles
The contact owns a 2011 Toyota Prius. While driving at any speed, the contact stated that the vehicle would suddenly accelerate forward while pressure was being applied to the brakes. The dealer advised the contact to bring the vehicle in for diagnostic testing. The manufacturer took a complaint on the contacts behalf but provided no further assistance. The current mileage was 2,000 and the failure mileage was 900.

- Long Island, NY, USA

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