2016 Toyota Prius engine problems

Filed Oct 30, 2026 · Engine · IN

The front exhaust pipe assembly (heat exchanger) on my 2016 Toyota Prius leaked engine coolant internally into the exhaust system. Toyota has documented this condition in Technical Service Bulletin T-SB-0135-19 ("Low Coolant, MIL ON DTC P148F00, and/or Poor Heater Performance") for 2016-2019 Prius vehicles and released a redesigned replacement part (17410-37D40). In [October 2026], at about [97,000] miles, I found the engine coolant reservoir was emptying about every night (nearly a full reservoir) with no external leak. A shop pressure test found no leak. Coolant collected inside the tailpipe after the car sat overnight, and white steam came intermittently from the exhaust while driving. The car stored code P148F00. On XXX a Toyota dealer ([DEALER NAME], [XXX]) confirmed coolant leaking from the front exhaust pipe heat exchanger, per T-SB-0135-19, repair order #[RO NUMBER], and quoted $1,870 to replace the front exhaust pipe with the updated part. My concern is that a vehicle losing coolant this fast can run low without warning and overheat while driving, which can cause engine damage or loss of power, and the white steam from the exhaust may reduce visibility for drivers behind. I also worry that coolant entering the exhaust damages the catalytic converter. The car has been serviced regularly, and the leak was not caused by an accident or impact. Toyota covered this repair under its emissions warranty for 8 years/80,000 miles, but my car is past that and Toyota has declined goodwill coverage (Toyota case #XXX). I'm reporting this so the federal safety agency can see that the failure is happening in vehicles outside that warranty period and can evaluate whether it is a safety defect. Vehicle: 2016 Toyota Prius, VIN [XXX] Component: Engine and engine cooling / exhaust system Crash: No. Fire: No. Injuries: No. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Mar 13, 2025 · Engine · GA

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.

Filed Jan 25, 2025 · Engine · CA

Refer to TSB 0135-19 dealer denied repairing under the California emissions defect and performance warranty.

Filed Jan 16, 2025 · Engine, Steering · PA

My car suddenly stopped in the middle of the road with message "Hybrid system stopped steering power low". Safety concern to this happen on the middle of road during rain or cold.

Filed Jul 9, 2024 · Electrical, Engine · AZ

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.

Filed Jun 8, 2023 · Engine · CA

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.

Filed Mar 7, 2023 · Acceleration, Engine · TX

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.

Filed Aug 23, 2022 · Engine · GA

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!!

Filed May 23, 2022 · Engine, Transmission · OR

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.

Filed Jun 9, 2021 · Electrical, Engine · WA

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/