2018 Kia Niro: engine overheating

Filed Sep 21, 2025 · Engine · NC

Just before Hurricane Helene, I brought my 2018 Kia Niro Hybrid to Asheville Kia (NC) after noticing coolant loss and white smoke coming from the exhaust. The dealership charged me $1,400 for a repair involving new gaskets and the EGR cooler. Within a month, the same symptoms returned. I returned to the dealership and explained I believed the original issue had not been resolved. I had done research and found reports of similar problems in other Niro Hybrids. I specifically mentioned the coolant heat exchanger as a possible source, but they dismissed my input and pushed a $3,500 muffler system replacement. I asked for diagnostic proof, and they initially showed a photo of the muffler with no visible leak. Later, they claimed a "small leak" was found during a pressure test — but the symptoms didn’t align. I then took the vehicle to John’s Kwik Lube in Spruce Pine, NC, where they confirmed the coolant heat exchanger was faulty — exactly what I had originally suspected. They repaired it with a simple workaround for under $200, and I’ve had no issues since. The faulty component (coolant heat exchanger) is not available for inspection, but I retained diagnostic records, pressure test results, and screenshots of the dealership’s estimate. I also documented that Kia’s quote system does not allow access to past service quotes, so I had to screenshot everything manually. The only symptoms were coolant loss and white smoke from the tailpipe, beginning shortly before the storm in September 2018, and recurring until the final repair later that year. The problem was confirmed by an independent mechanic, and partially acknowledged (though misdiagnosed) by the Kia dealership. No police or insurance inspection was involved. This situation posed a safety risk due to reduced visibility, potential engine overheating, and exposure to coolant vapors, especially during uphill driving. The issue is known among Kia owners and appears to be a recurring design flaw in the Niro.

Filed Oct 31, 2024 · Engine · WA

Internal combustion engine coolant leaking out exhaust. The heat exchanger located in the catalytic converter system is leaking, leading to the ICE coolant draining. This leads to the engine overheating, and damage. Signs of the issue started with the coolant level lowering quickly, then the car heater stopped working. This confirmed by an independent mechanic.

Filed Mar 21, 2024 · Engine · WI

Coolant leak within the heat exchanger of the catalytic converter. Increases likelihood of overheating and engine damage. Especially when driving long distances, or within heavy traffic. Increases emissions as burning off coolant within exhaust.

Filed Sep 28, 2023 · Engine · 74,000 miles · WI

The contact owns a 2018 Kia Niro. The contact stated while driving approximately 65 MPH, the vehicle started shaking and vibrating abnormally. The contact stated that the accelerator pedal was depressed; however, the vehicle failed to respond as needed. The contact stated that the message "Engine Overheating - Request Service Now" and "Engine Control System" was displayed. The contact had taken the vehicle to an independent mechanic where it was diagnosed and determined that coolant had intruded into the engine block and the engine needed to be replaced. The vehicle had not been repaired. The contact attempted to contact the manufacturer but was unable to reach a Representative. The failure mileage was approximately 74,000.

Filed Apr 14, 2023 · Acceleration, Engine · MD

The car can slow down suddenly in the middle of traffic even if I accelerate. The engine has a problem according to the mechanics who was trying to fix my car twice without succes. The car does not hold coolant liquid for more than 15 minutes. It looks like the coolant is staying somewhere in the engine. It overheats too. Yes the car is available for inspection upon request. It's a high risk because the car can suddenly slow down in the middle of traffic or when leaving a light turned green. And the last time I drove it there a weird smell. Yes, an independant service center located at College Park Maryland informed me about the issue. The vheicle or compenent has not been inspected yet by the manufacturer, police, insurance representative or others. When the car starts slowing down in the middle of traffic, I feel a kind of vibration first on the gas peddale and comes up the engine light. This happened last month

Filed Jan 20, 2023 · Engine · CA

On Kia Niro, there is a part called the Exhaust Heat Recovery System (EHRS). This part pumps coolant into the exhaust system. If this particular piece fails, coolant in then pumped into the exhaust, burned up, and exits through the tail pipe. This piece failed on my car, which lead to coolant being burned in the tailpipe without my knowledge, which ultimately lead to no coolant in the engine and overheating and breaking down on the highway. After a full engine replacement, my car is still rapidly going through coolant. I imagine that this could lead to a car fire. I still have the faulty part installed in my car, however I am looking to replace it asap. While not 100% confirmed, my dealer is "pretty sure" that piece is what is causing the rapid loss of coolant in my car. This piece has not been inspected by the manufacturer, police or insurance representatives. There were no warning lamps, messages or other symptoms to alert me to this problem. I only found out about this piece and its failure rate after a full engine replacement.

Filed Sep 12, 2021 · KY

My 2018 Kia Niro EX keeps overheating. We purchased the vehicle July 21st 2018. Three months after purchase, the vehicle dies, flashing warning lights and a message appeared to shut the engine off. Our car was towed to the dealership we purchased it from. After over three months, the dealership calls and tells us to pick the car up from them. The entire engine had to be replaced. We sued Kia Motors through the lemon law. We settled for the payment option because the engine was replaced. Now, our hands are tied due to once we took the cash settlement, we were no longer able to take legal action again if we had any additional issues. Over the course of the last three years, we had to have it repaired for a wiring issue, now, our vehicle continually overheats. Our dealership where we purchased the vehicle does not have a hybrid technician to work on it. We have to drive to another location of theirs to have it serviced. That location is over an hour drive. Our car is unable to be driven to have it properly service by the correct technician. There is an online forum, www.kianiroforum.com. This forum explains in detail what type of issue the consumer is experiencing with this vehicle. I am reaching out due to this overheating issue could cause serious harm to someone. We have spoken with Kia corporate headquarters, their advice is to have it looked at by a Kia dealership and they will go from there. We have exhausted all of our options to have these issues looked into and now reaching out to you for assistance. Myself included, it appears this vehicle has many many issues and needs to be brought to someone’s attention that has the power to get something done.