2018 Kia Optima transmission problems

Filed Oct 21, 2026 · Engine, Transmission · CA

My 2018 Kia Optima has the Theta II 2.4L engine. In February 2026, the dealer performed an engine/powertrain computer reprogramming. In August 2026, the engine failed and the vehicle was taken to an authorized Kia dealer, where the engine was replaced under the Theta II engine warranty. The vehicle was at the dealer from August 8 until the repair was completed on September 29, 2026. When I picked up the vehicle on October 9, it felt shaky and vibrated on the drive home. On October 11, the vehicle began giving off a distinct, unfamiliar smell that is not like burning fuel or oil. On October 21, I found the vehicle leaking an opaque, milky tan fluid onto my garage floor. The type and source of the fluid are UNKNOWN. I have photos of the leak. My family and I have stopped driving the vehicle because we believe it is unsafe. We were driving it with our children before these symptoms appeared. Given the history of Theta II engine failures, we are concerned about the risk of engine failure, stalling, or fire while driving. The new symptoms have not yet been diagnosed or confirmed by a dealer. I am arranging for the vehicle to be towed to a Kia dealer for warranty diagnosis. The vehicle and leak are available for inspection. I have reported these issues to the manufacturer under an open customer case.

Filed Jun 4, 2025 · Electrical, Engine · ID

There is already the theta 2 campaign on my Kia optima but Kia is not upholding their warranty for a new engine. Kia customer care told me that untill my car actually throws a rod then they will not fix it. So I could be doing 80 down the freeway and jeopardize not only my safety but everyone else's for them to uphold their lifetime warranty? Also upon doing further investigation and I don't know how many cars this pertains to but the fuse box in my 2018 actually belongs to a 2016 which if you look it up yes they are comparable but don't offer all the same functions or power that my 2018 needs to run I fully believe Kia knew this when they were being built on the factory line because it just so happens that there is about 6 different versions to the pcb relay that can fit from a 2016 to a 2020 k5 but for some odd reason every car got something different why?

Filed Jan 20, 2025 · Acceleration, Engine · MS

My engine burns oil very bad. Black smoke comes out of my tailpipe and I burn through 5 quarts in less than a thousand miles. I just got my oil changed two weeks again and I just had to add more oil to my car bc it was empty. I’ve had to replace the spark plugs twice due to soot build up. I can’t afford a new car I’m 17 and can barely afford the maintenance let alone a whole new engine. Have spoken to many mechanics and they all say the same thing “it’s a Kia it’s gonna burn oil” ITS A KNOWN ISSUE. And yet Kia will not resolve it bc they don’t want to spend their own money to fix their mistake. I got an estimate for a new engine which is basically crucial and it’s over three grand. No matter where I take it everyone always says the same thing- to get rid of it before it’s too late. But I simply cannot afford to do that and I know my car is not the only one with this issue so many other people with the same car/engine have the same issue. 2.4 L GDI !!!!! I wish someone would have warned me before buying Kia. A recall to fix this issue is needed now. I lose control of the speed sometimes. I will keep my foot at a set position on the throttle and the engine will take off because it’s jumping to the usual power it should have. ( it has reduced power most of the time bc of the struggling engine) sometimes on the highway I’ll get a sudden burst of power and I have to let off the accelerator. Not safe at all

Filed Jan 18, 2025 · Transmission · MS

It burns oil constantly. I constantly have to get new filters put on because they become black very quickly same with the oil itself. The engine has a tic and I know other people with optima’s that have the same problem. I burn through 4 quarts in two weeks- less than 600 miles.

Filed Oct 1, 2024 · Engine, Transmission · 76,270 miles · FL

The contact owns a 2018 Kia Optima. The contact stated while driving approximately 40 MPH, the accelerator pedal was depressed; however, the vehicle failed to respond as needed. The contact stated that there was an abnormal growling sound coming from under the floorboard, and the engine was making an abnormal knocking sound. The contact stated that the RPM gauge was revving high while depressing the accelerator pedal; however, the vehicle failed to respond. The contact pulled over and turned off and restarted the vehicle; however, the vehicle was not running normally. The contact stated that the failure was a recurring failure. Additionally, the contact stated that vehicle was consuming approximately one quart of engine oil per week and the transmission was hesitating and was making the vehicle jerk while shifting gear. The contact had taken the vehicle to an independent dealer, but the vehicle was not diagnosed or repaired. The manufacturer was informed of the failure. The failure mileage was 76,270.

Filed Sep 20, 2023 · Acceleration, Engine · MS

Car will NOT go pat 60mph and i haven’t had this car just over 6 months. And the camshaft sensors are gone out. Smoke comes out the pipe when mash on gas…. It is really a bad vehicle. And Southeast auto refuses to fix it. I really honestly think the motor is bad in it. Because I been having issues with it since I had it

Filed Aug 8, 2023 · Engine, Fuel system · TX

I'm reporting these issue pertaining to the engine within the first 3 weeks AFTER the engine replacement recall was serviced and completed. The vehicle was exhibiting the same defects and major health and safety hazards as before the new engine. Intermittent engine failure, even worse, while i was trying entering the hwy at speeds of 45-50 miles it jerked very violently and loss total power while vehicles were behind me nearly rear ended. Prior to this I reached out multiple times to have it serviced at again. The original service department didn't respond, so I called other service departments and was told it needed to be serviced by the original dealership/service department that replaced the engine. I had the vehicle in normal working conditions a few days before it began exhibiting the same problems as before the engine replacement. It was in operable condition but still stalling and refusing to crank unless primed, until it ultimately just would not crank at all and is back in the same condition it was before the new engine but it is not locked up currently. The time frame and Milage between first experiencing the issues to now, March 2023-64745 Started shuddering, loss of power while driving, but would crank right back up without issues. Happened a few times, charged up battery thinking is was am electrical issue. April 2023 More frequently the issues occurred, still same severity levels. May 2023 Began happening every time at an idle, whether I was at a fast food in drive through placing an order, or to wash the car. Every time at an idle this would happen, and would take a few times of trying to start the vehicle and after about 5 seconds of cranking it would catch and work. I began placing the vehicle in neutral while at idle and it would assist In the stalling out sometimes. After a few days of this it refused to crank due to the engine locking up. Milage at this time was 68048. Aug 2023-New engine, drove about 2k miles-70207 current

Filed Jun 1, 2023 · Acceleration, Transmission · CA

Ever since I got my car I’ve had black oil since the start . Second my car breaks on its own at times 3rd my car system keep breaking down as the sparks leaking in some where has this issue since bought it 2 years ago low miles

Filed Mar 3, 2023 · Transmission · 60,000 miles · NC

The contact owns a 2018 Kia Optima. The contact stated that while driving at an undisclosed speed, the vehicle was jerking. The vehicle was taken to the dealer; however, no cause for the failure was found. The vehicle was then taken to Battleground Kia of Greensboro (2927 Battleground Ave, Greensboro, NC 27408) but no cause for the failure was found. The vehicle was not repaired. The manufacturer was made aware of the failure. The failure mileage was approximately 60,000.

Filed Oct 26, 2022 · Transmission · AL

UNKNOWN When slowing to a stop, the vehicle spontaneously makes a sudden jolt, throwing passengers forward. It’s as if the the transmission malfunctions when down shifting and results in engine braking.