2016 Kia Optima: sudden loss of power

Filed Nov 5, 2026 · Engine · AZ

My Kia experienced catastrophic engine failure while I was driving on the freeway, creating an extremely frightening and dangerous situation. The sudden loss of engine power put my safety and the safety of surrounding motorists at risk, as I was traveling at freeway speeds when the engine gave out. Leading up to the failure, my vehicle experienced excessive oil consumption despite regular maintenance. I was repeatedly adding oil between scheduled oil changes. Previous repairs, including replacement of spark plugs and a thermostat, did not resolve the underlying issue. Following the engine failure, a Kia dealership reported a cracked engine valve and multiple severely damaged or melted spark plugs, including spark plugs that had recently been replaced. These findings raise serious concerns about progressive internal engine damage and a potentially defective engine. Despite my concerns regarding known Kia engine defects and possible connecting rod bearing issues, the dealership stated it could not perform the bearing clearance test due to the condition of the valves. My case was never submitted to Kia Techline for further investigation. I was initially instructed to provide oil change and maintenance records for consideration of engine replacement assistance, only to later be told that excessive oil consumption was not relevant to my claim. I am extremely concerned that a potentially defective engine experienced progressive damage before suddenly failing on the freeway, placing my life and others at risk. I am requesting that the federal safety agency investigate this failure and determine whether it is related to known Kia engine defects or an unresolved safety issue affecting other vehicles.

Filed Oct 10, 2026 · Engine, Transmission · TX

Severe engine defect (Theta II 2.4L GDI). Sudden total loss of power, metallic knocking, severe oil consumption, and imminent catastrophic failure while driving, creating a high safety risk. Vehicle is currently out of service in [XXX]. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Aug 25, 2026 · Electrical, Lights · FL · crash

Vehicle was purchased in 2023. AC blower failure occurred for the first time in June 2024 and was repaired by PepBoys. On 4/2/2025 the ve3hicle had an active recall event when the engine seized on the highway because of a faulty oil pump/filter, Engine was replaced 4/17/2025 under that recall. Kia advised at the time that the wiring harness should be replaced due to electrical issues at the time but said that there was no recall for that work. At the time, there were no electrical failures of steering, brakes, all power etc. Nor did we know that those were a possibility. The wiring harness quote was $7,000, over the cost of the vehicle. It was decided to continue repairing the electrical issues as they came up, it was assumed that the fuses would blow before there because a safety or total vehicle failure, as automobiles are designed that way. 8/4/2026 the vehicle experienced a complete and total loss of power resulting in a traffic crash into another vehicle as the brakes felt like you were trying to push a wall rather than a pedal. There was minimal physical damage to the other car and the kia, the other driver got my husband's insurance information and then drove off. The car did startup after ~30 minutes or so and was driven home, but taken to the Kia dealership the next day. It was said that the blower motor overheated and melted a portion of the electrical junction box under the hood and that it was unsafe and dangerous to drive. Kia said that there were no active recalls for this work. the federal safety agency SC351 seems very similar to this issue that has plagued this car since the beginning. We would ask that Kia incorporate this vehicle and others outside of the year/model ranges in SC351 that have similar failure mechanisms as this seems common.

Filed Aug 21, 2026 · Brakes, Electrical · CA

While driving at highway speeds on the freeway in San Diego, the engine of my 2016 Kia Optima catastrophically seized without warning. I instantly lost all power steering, brake assist, and electrical power, creating an immediate life-threatening emergency. The vehicle was towed to a Kia dealer. Corporate Techline and the dealership are refusing to perform the mandated settlement rod bearing test and are falsifying paperwork to deny the safety remedy.

Filed Aug 5, 2026 · Engine, Transmission · FL

The engine assembly completely seized and the vehicle is currently stored at an independent repair shop . While traveling at high speed on Interstate 4 on July 24, 2026, the vehicle suffered a sudden, catastrophic loss of power and stalled in live traffic, creating an immediate threat of a high speed rear end collision. An independent service center officially confirmed the engine seizure after a dealership failed to perform an inspection during an eight hour wait, and no law enforcement or insurance inspections have occurred. Prior symptoms included severe, recurring oil loss requiring constant manual additions of oil between regular service intervals (most recently serviced in June 2026 at a kia dealership), and eventually the car completely shutoff on July24.

Filed May 24, 2026 · Engine · FL

While accelerating onto the highway in my 2016 Kia Optima 2.4L, the vehicle suddenly lost all engine power without warning. The vehicle would no longer accelerate and I was forced to coast and brake to safety. Immediately after the engine shut off, the check engine light, oil light, and battery light illuminated on the dashboard. After the incident, the vehicle would not restart or crank at all. The electrical systems, dashboard lights, and chimes still function normally, and the battery is new. The vehicle had proper oil level at the time of failure. No warning signs were present prior to the sudden loss of power. This failure created a serious safety hazard because it occurred during highway acceleration and left the vehicle unable to maintain speed or move out of traffic safely. Based on the symptoms and sudden engine shutdown, I am concerned this may be related to the known Theta II engine issues associated with Kia Optima vehicles.

Filed Feb 3, 2026 · Engine · PA

The engine stalled without warning while I was pulling out of my driveway into the street, creating an unsafe condition due to sudden loss of power. After waiting briefly, the vehicle restarted and was moved back into the driveway. It was towed the following day due to loss of confidence in safe operation. The vehicle was diagnosed with engine failure consistent with known defects affecting Kia Optima vehicles equipped with Theta II engines. Kia denied coverage under the extended engine warranty / class action settlement solely because the KSDS (PI1802 ECU update) had not been installed prior to the failure. As the second owner, I was never notified of this update before the incident and had no opportunity to complete it. This failure was sudden, unanticipated, and safety-related. I am submitting this complaint to document an engine stall and loss of power condition posing a safety risk.

Filed Jan 31, 2026 · Engine · CA

My 2016 Kia Optima experienced a sudden catastrophic engine failure in July 2025. The failure is consistent with widely reported Theta II engine rod bearing defects that cause engine seizure and stalling. The vehicle did not receive the Knock Sensor Detection System (KSDS) update prior to my ownership, and I was never notified of this critical safety-related update. The engine failure occurred without warning and could have resulted in loss of power while driving, creating a serious safety risk. This vehicle model year has a documented history of engine defects and class action settlements related to premature engine failure. I believe this represents an ongoing safety defect. I am requesting that the federal safety agency review this failure as part of its investigation into Kia Optima engine defects.

Filed Jan 14, 2026 · Engine · GA

While driving my 2016 Kia Optima, the vehicle experienced a sudden and complete loss of engine power and stalled without warning. At the time, I was Door Dashing for income. The engine seized and the vehicle came to an immediate stop in the middle of 4925 Wolf Creek Dr SW, Atlanta, GA, a narrow two-lane road with limited street lighting. I was forced to remain stopped in the roadway in darkness for over an hour while multiple oncoming vehicles passed by, creating a serious safety risk. The vehicle could not be restarted and had to be left on the roadside overnight. The following day, the vehicle would only start briefly when jump-started, ran for approximately 15 seconds, and shut off again. It could not move and was towed to an authorized Kia dealership. At the dealership, technicians jump-started the vehicle, performed diagnostics, added engine oil, cleared codes, reset adaptive values, and conducted a test drive. During that test drive, the engine seized again, and the vehicle had to be towed back. Kia approved a full engine replacement under its extended engine warranty, acknowledging engine failure consistent with known defects. However, after the engine replacement, the vehicle would not start at all. Kia stated oil intrusion from the failed engine damaged electronic components, leaving the vehicle non-operational. Kia denied coverage for the resulting damage and issued an estimated $6,000 repair bill for engine harness, injector sub-harness, and ECU replacement. The vehicle remains inoperable following an approved warranty repair. This incident involved sudden loss of propulsion while driving, occurred without warning, resulted in repeated engine seizure, and left the vehicle disabled in traffic at night. This appears consistent with known Kia engine defects and presents a serious safety concern that warrants investigation.

Filed Dec 9, 2025 · Engine · OH

My 2016 Kia Optima is experiencing severe internal engine oil consumption that matches known issues Kia has recalled and extended warranties for. The vehicle loses 1–3 quarts of oil every few days with no external leaks. A repair shop found a P0304 cylinder 4 misfire, P0010 cam actuator code, and spark plug damage caused by oil entering the combustion chamber. They confirmed internal engine damage and abnormal oil consumption. The Kia dealership refused to assist due to mileage, even though this issue matches the engine defects covered under Kia’s litigation settlement and warranty extensions. The excessive oil consumption creates a dangerous safety risk, including engine stalling, loss of power, and potential engine seizure while driving. I am requesting the federal safety agency review because the vehicle’s condition is unsafe and part of a widespread engine defect.

Filed Aug 22, 2025 · Engine · TN

Engine began jumping during driving and loss power. No dashboard illumination warning lights and the temperature gage showed normal operating temperature. Car was not accelerating properly. Had to maneuver carefully to prevent being ran over. Engine light illuminated showing misfire. Replaced ignition coil pack and spark plugs. Driving again, car stalled. No dashboard warning lights. No high temperature on gauge. Narrowly missed being hit by a semi as there was absolutely no warning and we were on an Interstate bypass ramp with nowhere to pull over!! Towed car to dealership for diagnosis. Results: engine blown, turbos gone, and the catalytic converter is holding oil. Dealer is stating this is not covered under the extended warranty from Kia as its not connector rod bearing issues and that the piston rings failed. However, they stated the turbos got "too hot" and they failed. The gauges have never shown that the car was running hot. I have a sworn statement from my mechanic stating this is absurd and a valiant attempt to not pay for what would be the second warranty replacement of my engine. The piston rings failed as a result of the connector rod bearing failure. The "too hot" temperature that damaged the turbos was likely caused by the same bearing issue. The heat from the bearings unseated the piston rings and allowed the engine to dump its oil causing the engine to fail. I highly recommend that you open an investigation into these issues. The car not accelerating and losing power at interstate speeds is a very serious and dangerous issue.

Filed Aug 18, 2025 · Engine, Fuel system · AZ

I am filing this complaint to urgently bring attention to a serious safety and mechanical defect with my Kia vehicle's engine and fuel system. My engine is excessively consuming oil, to the point where it poses a significant risk of engine failure, which could result in a loss of power while driving and create a hazardous situation on the road. Details: I consistently have to add 5 quarts of oil approximately every month. During regular oil changes, there is barely any oil recovered from the engine, suggesting the oil is being consumed or burned internally. I took the vehicle to AutoZone for diagnostics, and they confirmed the engine is burning oil. They also mentioned it could be related to a rod or piston ring issue. There are no visible leaks under the vehicle, and the oil is not being expelled externally—it's being consumed by the engine. This issue is not normal wear and tear. It's a systemic engine defect that is causing rapid oil loss and is likely to lead to engine seizure or failure if not addressed. This level of oil consumption is not just expensive—it is dangerous. A sudden loss of engine power could cause an accident, especially at highway speeds. I am deeply concerned for my safety and the safety of others on the road. Urgency: I am requesting the federal safety agency to investigate this issue and consider initiating a recall for affected Kia vehicles. I am not the only one facing this problem—online forums and consumer reports are filled with similar complaints from other Kia owners. This is a critical engine/fuel system safety defect that must be addressed immediately before someone is injured or worse due to engine failure while driving. Thank you for your time and attention to this matter. I am available to provide service records, photos, and further documentation upon request. Sincerely, [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)