There is a known issue with this vehicle and the fix by KIA is not safe nor fair to the consumer. Kia's knock sensor recall centers on the Knock Sensor Detection System (KSDS) software update for Theta II GDI engines. The update listens for rod bearing wear, triggers a check engine light and limp mode via Code P1326, and extends the engine warranty up to a lifetime or 15 years/150,000 miles. My problem is that we had to car in on May of 2026 after in went into limp mode. They updated the software. The car again went into limp mode on 10/21/2026, they updated the software again. My focus here is the fact that it is a known issue and they say it still does not meet the parameters for an engine replacement. It is a severe issue that is dangerous and inconvenient to the driver. You are afraid to take it on a trip or even take it on a highway. My 20 year old daughter drives this to college. Can you imagine a car going into limp mode on a majory US highway? Limp mode essentially does not allow a vehicle to go above 2K RPM. You cant go up a hill over 35 and on a highway, on a flat road you "might" be able to go 55 MPH. My daughter goes to college 4 hours away. This creates a very unsafe, dangerous and inconvenient environment. KIA is hoping that they can buy time until these vehicles fail for some other reason and they dont have to pay the cost for a new engine.... ALL at the consumers peril. To put this in perspective, if you have a vehicle with a "low tire pressure" warning, does lowering the sensors parameters fix the problem.... No, it just turns off the warning and you are driving a car with low tire pressure.
2015 Kia Optima: check engine light
140 of the 1,011 complaints about the 2015 Kia Optima describe check engine light.
- owner complaints
- 140
- of this car's complaints
- 14%
- typical repair cost reported
- $6,800
- typical mileage
- 98,375
- recalls
- 1
Check engine light by model year
What owners say
P1326 code flashing engine light knock sensor went out 3 times in 6 months and just replaced it again and this time engine light didn't go off I was reading that there was a recall on this but apparently mine doesn't state it. Car cannot pass emissions if engine light is on and the 15th of June is approaching. The car doesn't make any sounds or nothing.
The contact owns a 2015 Kia Optima. The contact received notification of the federal safety agency Campaign Number: 21V331000 (Service Brakes, Hydraulic); however, the part to do the recall repair was unavailable. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The contact stated that while starting the vehicle, the check engine warning light illuminated. The vehicle was take to O'Reilly's to be diagnosed. The DTC: P1326; was retrieved. The contact attempted to start the vehicle, but the vehicle failed to start. The contact researched online and found the federal safety agency Campaign Number: 20V543000 (Service Brakes, Hydraulic). The dealer was contacted, and it was confirmed that the vehicle was included in the federal safety agency Campaign Number: 20V543000 (Service Brakes, Hydraulic); however, the dealer refused to repair the vehicle because the vehicle was not currently registered and additional repairs were needed before a recall repair could be performed. The vehicle was being towed to the dealer. The vehicle was not yet repaired. The manufacturer was made aware of the issue. The failure mileage was approximately 137,000.
The contact owns a 2015 Kia Optima. The contact stated that while driving at 40 MPH, there was smoke coming from underneath the hood, and the engine overheated. The check engine warning light was illuminated. The contact was able to pull over to the side of the road and add coolant to the coolant reservoir. The vehicle slowly started and was driven to the destination. The contact stated that the engine was overheating if driven for more than 10 minutes. The vehicle was taken to an independent mechanic, where it was determined that the vehicle was experiencing excessive coolant consumption, and coolant was added as needed. The mechanic determined that the failure might be related to the engine. The vehicle failed to start and was undrivable. The vehicle was not repaired. The dealer was contacted and referred the contact to the manufacturer for assistance. The manufacturer was contacted, and a case was filed. The failure mileage was approximately 124,000.
The contact owns a 2015 Kia Optima. The contact stated that while driving at an undisclosed speed, the engine seized, and the vehicle stalled. The vehicle was able to coast to the side of the road. The check engine warning light and several other warning lights were illuminated. The contact raised the hood, and there was a burning odor coming from the engine. The vehicle was towed to the place of employment. A mobile mechanic arrived at the place of employment and used a handheld code reader to diagnose the vehicle, but no DTC was retrieved, and no cause for the failure was determined. The starter was replaced; however, the vehicle failed to restart. The vehicle was towed to an independent mechanic, who diagnosed that the engine had failed and needed to be replaced. The vehicle was not repaired due to the cost. The contact stated that the vehicle was purchased six months prior to the failure. The manufacturer was not made aware of the failure. The failure mileage was approximately 96,000.
My Kia OptimaLX had no check engine light not running any different no warning or light indicators turned on but car caught on fire while parked after only driving less than 5mins less than 1 mile from home. Entire front dash burned all the way to the gear shift. Every recall notice recieved was taken care of as soon as I was notified that there was a recall and they had the part to change it out. The engine was part of the recall and was replaced and a fuse module box was replaced 1 month or less from the time of the fire. Car is considered a total loss from insurance company.
My 2015 Kia Optima (VIN [XXX] ) experienced sudden engine failure and stalled while driving at approximately 90,000 miles. There was no oil pressure warning light and no knocking prior to failure. The check engine light illuminated shortly before the stall. Kia is denying engine coverage solely because an ECU/KSDS update was not performed. I was never notified of this update because Kia had an incorrect address on file for me. This failure is consistent with known Theta II connecting rod bearing defects that have resulted in recalls and warranty extensions. I believe this is a safety-related defect and am requesting review. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
The contact owns a 2015 Kia Optima. The contact stated that while driving at an undisclosed speed, the engine seized. The contact stated that the check engine warning light was illuminated several minutes before the engine seized. The vehicle was towed to an independent mechanic, where it was diagnosed with engine failure. The contact was informed that the engine needed to be replaced. The vehicle was not repaired. The vehicle was then towed to the dealer where it was diagnosed with engine failure. The contact was informed that the engine needed to be replaced. The vehicle was not repaired. The contact was informed that the repair was not covered under warranty. The manufacturer was made aware of the failure but provided no assistance. The contact was informed that because the previous owner did not have an unknown software update performed, the repair was not covered under warranty. The failure mileage was approximately 138,000.
The incident took place on Sunday, December 30th. I was driving to pick up my children from their father and on our way home my car stopped accelerating entirely. This had only happen one other time a few days prior. I was in a gas station parking lot and initially when I turned my car on and went to put it into drive it wouldn’t accelerate. I thought that was odd so I did the only thing I knew how to, I checked my oil levels. Levels were full and no other issues were there. The check engine light had popped up when I turned my car back on but my car did accelerate so I thought nothing of it. I took my car to auto zone for a diagnostic and they told me my “B cam shaft” sensor needed to be moved and that could be causing the engine light to come on and ticking in my motor. I called a few shops getting quotes and eventually was forced to tow to the closest shop to me after my car refused to start overall. They replaced the battery and the b cam shaft censors and still were unable to get the car started. They told me 3 recalls were open on my car, including the motor and to have it towed to Kia for a full replacement. After calling Kia to have the repairs done, they refused me service based on a previous owner not handling prior recalls.
12-01-2025 driving to work in the morning approx 7:00A.M. and turned on the heater and had a very strong smell like fuel so immediately turned it off. Cracked my windows to air it out and then was super cold again and had turned on the heater to try again. Immediately had to turn it off and rolled windows down to air it out because the smell was intense and had started to feel nauseas. Later in the day, about to head to lunch and had started the vehicle and smelt a lot like gas and turned it off and had someone come out to double check the smell. Co worker had strong smell from the hood area and looked underneath the car and can see a little drop puddle. Opened the hood and lifted the cover to engine where you can see the leakage coming from the center hose and spill puddle. Service tech came to take a look and advised its the fuel feed to the high pressure pump. This is a safety concern because fuel is extremely flammable and can put myself in dangerous situation of firing igniting in the car or hurt others around. No check engine light and prior the vehicle incident car has been consuming oil putting in about 1- quart a week or so with commute miles about 270 weekly.
The vehicle unexpectedly stalled while idling at a complete stop, posing a serious safety concern. Shortly afterward, the check engine light illuminated. These events occurred around 78,000 miles. Prior to the stall, the engine had been making occasional knocking or tapping noises, particularly at idle. The vehicle was immediately taken to a certified Kia dealership, where a technician diagnosed the issue as engine failure consistent with a known manufacturer recall affecting this vehicle model and year. A recall claim was submitted to the manufacturer, but the repair has been delayed for over a month with no authorization to proceed. No loaner vehicle has been provided. The engine failure puts the driver and others at risk, especially if the vehicle were to stall during active traffic conditions. The problem has been confirmed by the dealership but has not yet been resolved by the manufacturer. Inspection by the manufacturer is still pending. Warning symptoms included the engine light and knocking sounds, which began shortly before the stall occurred.
My motor bearing is knocking very loud I was refused service upon arrival dealer was making my service very complicated asking me to go dig up old receipts and various other things that was not actually caused for and I was at risk by driving the car there until it shut off due to engine failures when the car has fire risk and could possibly explode and they have confirmed it’s the engine but have not done any maintenance to my engine the check engine light flashes heavy non stop as well was even denied a loaner car still until today
Service bulletins that may apply
- Excessive oil consumption nu/gamma/theta/kappa engines
- Bearing clearance tester (BCT) procedures
- Pitstop: injector harness routing for PI1802Y/z and PI1803Y/z engine replacements
- Engine replacement instructions for DTC P1326 (PI1802Y/z)
- Excessive oil consumption nu/gamma/theta engines
- Partial repair of c-mdps motor, ECU, worm gear and/or steering column housing
- Product improvement
- Voluntary emissions service campaign - auxiliary canister installation and evap leakage test (SC189)
Related recalls
Engine
- What is wrong
- Kia Motors America (Kia) is recalling certain 2011-2017 Optima, 2012-2017 Sorento and 2011-2018 Sportage vehicles that previously received an engine replacement under recall number 17V‑224, warranty, or the Knock Sensor Detection System (KSDS) Product Improvement Campaign. The high pressure fuel pipe that connects to the fuel pump outlet may have been damaged, misaligned or improperly torqued during the engine replacement procedure, possibly causing a fuel leak.
- Risk
- A fuel leak in the presence of an ignition source can increase the risk of a fire.
- Remedy
- Kia has notified owners, and dealers will inspect and replace the fuel pipe, as necessary, free of charge. The recall began January 17, 2019. Owners may contact Kia customer service at 1‑800‑333‑4542. Kia's number for this recall is SC172.
Recall number 18V907000 · Recall details
Questions about the 2015 Kia Optima check engine light
Is check engine light a common problem on the 2015 Kia Optima?
140 of 1,011 owner complaints about the 2015 Kia Optima (14%) mention check engine light. The model year with the most reports is 2013.
How much does it cost to fix check engine light on the 2015 Kia Optima?
Owners who mentioned a price put the repair at about $6,800 (median of 8 complaints that include a dollar amount). Costs vary with mileage, warranty and where the work is done.
Is there a recall or service bulletin for this on the 2015 Kia Optima?
There is 1 recall and 59 service bulletins for the same area of the car. Check them below with your VIN.
Other symptoms on the 2015 Kia Optima
Engine failure 244Knocking 149Stalling 140Fire or smoke 97Loss of power 59Won't start 42Oil consumption 39Jerking 25Warning lights 22Won't shift 19Headlights 17ABS 15Hesitation 13Power steering loss 12Airbag light 10Fuel smell 10No deployment 9Brake failure 9Sunroof shattered 9Grinding brakes 8Overheating 8Steering lock-up 7Fuel pump 6Backup camera 5Power windows 5Shudder 5Pulling 5Wipers 5
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