2016 Toyota Prius

Water pump failed without warning and caused irreparable damage to the engine ("blown" engine requiring replacement). Vehicle began to stall and not respond to attempted acceleration while traveling on 4 lane divided highway, 55 mph speed limit. One "Maintenance Required" message was received the previous week, but disappeared. This is the same message that appears for routine oil changes. No other warning messages were noted at the time of the incident, no unusual noises, and no smoke or other sign of overheating. Driver was able to steer vehicle to safety, but this failure could result in stranding on a busy, dangerous interstate highway. For such a critical piece of the vehicle (i.e., the water pump), there should be obvious warning message(s) and dedicated monitoring of the equipment.

During summer months when temperatures are above 100 degrees when accelerating from a complete stop I can hear the engine rev and the RPMs increase but the vehicle will move at 1-2 mph. Even if the accelerator is to the floor. After 3-4 seconds the tires will squeal and the vehicle will be jolted forward then it will slowly accelerate. This happens occasionally and I have taken it to a Toyota dealership and a chain mechanic shop, neither have been able to recreate the problem. There are no warnings and no error codes. I have been stuck in the middle of intersections trying to turn left, I have not been hit, but I fear it will happen. There is a recall out for this issue on other Priuses and I believe the issue needs to be investigated further as there is another complaint on this site for the same issue and I have found it on other sites. I bought the car in fall of 2019 and this problem has been occurring since summer of 2020.

We were driving kids to camp and the thermometer light went on. It was blinking for a while, then turned off and then turned steadily on. We weren't sure what to do, so we called our trusty mechanic who said "bring it in right now." We did and it turned out that this was a broken head gasket. Our car is regularly maintained by a trusted Prius mechanic and has less than 78K miles, despite its age. From our mechanic: We found the engine coolant was low in the radiator. We filled the system and pressure-tested, found no external leaks. The thermostat and fans operate normally. We found 54 ppm HCs in the radiator initially, and after a test-drive we re-checked and found 110 ppm HC in the radiator. Combustion chamber gas is getting into the cooling system, typically a symptom of headgasket failure. The cylinder head needs to be removed to evaluate. FYI this is the first headgasket failure we have seen on the 4th gen Prius, but it is the same engine designation as the 3rd gen Prius, which has a pattern problem of headgasket failure. The expectation is that the failure is the same, but we need to open the engine to evaluate. Given the low mileage, it might be worth pushing Toyota for a goodwill warranty even though it is out of the official powertrain warranty period. I called Toyota and they refused to pass along a goodwill warranty.

On September 2022 (at 46K) Dealer did TSB related fix on my 2016 Prius. PFA for service record. They replaced Exhaust Front Pipe, which is suggested work from Toyota PFA for Toyota Technical Bulletin. T-SB-0135-19 At 51,747 on March 1st 2023 around 8 40 am, while we are driving on highway at 70 mph suddenly Check Engine Light, Coolant light, Hybrid related lights were on Vehicle lost the control, speed was dropping luckily we could safely stop the vehicle on the shoulder no Vehicle hit us from behind. Sudden stop of engine while driving on highway at 51K miles is safety issue. Toyota dealer could not provide additional details except Engine is over heating.

Shortly after having my Toyota serviced, I had an engine coolant warning sign appear. I checked and noted the coolant was gone. I bought coolant and filled the coolant tank. A week later, I see the light again. I have seen no leakage at all on the ground. I refilled the coolant and checked again the next morning. Again the tank is empty. I took the car to a local reputable service person and thus far, he sees no leakage outside of the car. This suggests to him a bigger problem, where the coolant is going somewhere it should not. If it is to the engine, I will have to replace that!!

Overheating light began flashing while driving 5/21/22. Drove to Napa Auto Parts and saw coolant reservoir was empty. Bought anti-freeze and filled reservoir. Upon arrival at destination, reservoir was empty again. Filled it again. Upon the next morning, reservoir was empty again. Took it to an auto-shop which found that the exhaust heat exchanger in my car has failed and is leaking coolant. Please see Applicable technical service bulletin, T-SB 0135-19. While the car is less than 96 months old, it is above 80k miles. I see this issue has been escalated in California, where the warranty is for 96 months and 150k miles. Want to report that the change in miles between states is disappointing. This issue is common and should be handled as a known recall, not just a known issue.

Vehicle stalls for 5-10 seconds when stopped at a red light. Seems to happen sporadically and is difficult to reproduce. There have been other reports of it online here: https://priuschat.com/threads/tsb-nimh-only-reduced-power-when-accelerating-from-a-stop.187455/ https://priuschat.com/threads/2017-prius-2-no-acceleration-movement-from-full-stop.209317/ https://priuschat.com/threads/2016-prius-2-stalling.200606/

CAR DOES NOT ACCELERATE FROM A STOP WHEN PRESSING THE GAS PETAL WHILE CAR IS IN DRIVE. THIS SEEMS TO HAPPEN ONLY IN THE SUMMER MONTHS. WHILE PULLING UP TO A RED LIGHT I SLOWED THE CAR TO A STOP. WHEN THE LIGHT TURNED GREEN I LET MY FOOT OFF THE BRAKE, CAR MOTIONED FORWARD A BIT BUT WHEN I PRESSED MY FOOT ON THE GAS PETAL THE ENGINE WOULD REV BUT WOULD NOT ACCELERATE IN ANY WAY. I PUT THE CAR IN REVERSE TO TRY AND GET OUT OF MAIN ROAD TRAFFIC BUT CAR CONTINUED TO HAVE NO POWER. I THEN PUT THE CAR INTO DRIVE, PUT MY FOOT ON THE GAS PETAL AND AGAIN, ENGINE WOULD REV BUT CAR WOULD NOT ACCELERATE. THIS IS VERY DANGEROUS AS THE CAR WILL ROLL FORWARD WHEN TAKING YOUR FOOT OFF THE BRAKE, SO YOU CAN ROLL INTO THE MIDDLE OF A HIGHWAY BEFORE YOU REALIZE THERE IS NO ACCELERATION PUTTING DRIVERS AT GREAT RISK OF BEING T-BONED WHILE ATTEMPTING TO TURN (ESPECIALLY LEFT TURNS). I HAVE TAKEN THE CAR TO TOYOTA TWICE AND SERVICE CAN NOT FIND ANY ISSUES AS NO CODES HAVE SHOWN UP. THE SOFTWARE WAS UPDATED AND ISSUE OCCURRED AGAIN AFTER UPDATE.