2018 Kia Sorento: misfire or rough idle

Filed May 5, 2026 · Engine · NC

2018 Kia Sorento, under 88,000 miles, with Theta II engine defect. KSDS update installed. Oil consumption issues requiring adding at least one liter of oil every 1,000 miles in between regular oil changes/ maintenance. Oil warning lamp does not illuminate at all or only blinks on for a second then stays off, even when oil is less than 1 liter. Noticed slight jerking/hesitation at acceleration for a few days, then experienced shaking and heard vibrations when breaking and idling. Within a few minutes, MIL appeared with audible warning, "Take this vehicle to a Kia dealership." Immediately parked car. Towed to Kia dealership. No record of DTC P1326 found, which would have qualified vehicle for new engine under PI1802 Y/Z Theta II Extended Warranty. Diagnostic found misfiring cylinder and fouled spark plug. Technician in the video stated "oil consumption." Due to absence of P1326 code, service manager suggests we replace fouled plug and return with the vehicle when the same issue happens again. This does not follow Kia's own guidelines in PI1802 Y/Z campaign for a couple of reasons. First, activation of the MIL in conjunction with the audio warning indicates the Knock Sensor P1326 code should have been generated and stored, but the warning system must have malfunctioned. Service dept. did not to inspect the knock sensor harness for damage or oil saturation which could have kept the code from registering. Second, Service dept. did not consider shaking and vibration as "engine noise," which would have required them to perform a BCT or test for connecting rod bearing noise, providing a pathway to request Techline PWA approve replacing the engine under warranty. Kia's Product Improvement Campaign for Theta II engines ought to prevent injury or death resulting from catastrophic engine failure. My vehicle presents clear evidence of engine failure progression at different stages. Rather than navigate the warranty via a Techline, Kia has advised me to continue driving.

Filed Mar 27, 2026 · Engine · NY

My car for the last 2 years has had multiple malfunctions with misfiring and replacement of head gaskets, pistons and more. Not to mention consistence oil concerns. On two occasions my family and I had to have the vehicle towed home over 200 miles because the car was not driving well. I have a [XXX] ghter who was with us at the time. The only warning lamp that ever triggered was the check engine. In October is when I was informed about a recall that was on my vehicle from KIA the corporation and I was told to have it towed to Kia in [XX [XXX] ey would replace my engine if the rod barring failed; and it did. Kia refused to pay for the engine and reported that I was misinformed. In December of 2025 I went through the Attorney General for mitigation to try and fix the engine- However, Kia reported because the engine manufacturer recall was not updated prior to October 30th or 2020 it was considered failure on the consumers part for not updating their address. However, I have documentation that the vehicle was sign for by myself on December 2nd of 2020. I have the car fax reporting that the car was surrendered by the previous owner on October 28th, 2020. Therefore, I was not the own when this manufacturer warrantee recall was in place or when it expired. So, I do not feel since i did not own the car when this was to be completed, that I should be responsible. Not to mention I am paying on the loan that financed this vehicle for the last 7 months while it has sat at KIA in [XXX] [XXX] ION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6) INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Feb 4, 2026 · Engine, Fuel system · IN

2018 Kia Sorento 2.4 GDI. In late 2024 a Kia dealer performed an oil-consumption test and confirmed the engine was burning excessive oil. In Feb 2025 the engine long block was replaced. Within about 4,000 miles the vehicle began setting P1326 warnings, misfiring, losing power, and struggling to climb hills. On a highway trip from South Carolina back to Indiana, the vehicle could barely maintain 30–40 mph on grades with the accelerator floored while traffic was moving much faster. The check-engine light returned repeatedly. The vehicle eventually died on an exit ramp and had to be pushed out of traffic and towed. I felt it was unsafe to drive but was repeatedly told by dealers that it was “OK to drive” or that the issue was “bad gas.” After visits to multiple dealers, the current Kia service center finally diagnosed a severely clogged exhaust. They report the manifold catalytic converter and underbody converter have broken down internally and are heavily coated in carbon/oil deposits, and state this likely came from the engine burning oil before and around the time of the rebuild. Exhaust temperatures have been recorded at very high levels, and the engine will only run briefly with an O2 sensor removed to vent exhaust; with the exhaust sealed it will not stay running. The dealer has warned there may now be internal engine damage from prolonged backpressure. The vehicle has been undriveable for many months and the failed converters are being retained and are available for inspection. My concern is that excessive oil consumption on these GDI engines is causing secondary catalytic-converter failure, extreme power loss, stalling risk, and possible fire risk from overheated exhaust components, even after engine replacement.

Filed Dec 11, 2025 · Engine · NC

Engine is burning oil at a rate of almost one quart per week. The engine can be felt shaking when driving. The engine light came on and states there is a P0303 Cylinder 3 misfired detected.

Filed Sep 9, 2025 · Engine · MI

KIA Sorento 2018 The vehicle experienced engine failure due to piston ring damage at approximately 111,500 miles. A Kia dealer diagnosed the issue with codes P0301 and P0304 and confirmed the engine requires full replacement. This creates serious safety concerns, including engine misfires, loss of power, and risk of stalling while driving.

Filed Aug 25, 2025 · Engine · NH

1. What component or system failed or malfunctioned, and is it available for inspection upon request? The engine misfired due to a broken valve in one of the cylinders. This failure occurred approximately two months after completing the scheduled 100,000-mile service at a Kia dealership. The affected parts (valve, cylinder components) should still be available for inspection by Kia or a third party. 2. How was your safety or the safety of others put at risk? The vehicle suddenly lost power and stalled in the middle of the highway while driving at normal speed. This created a dangerous situation where I could have been struck by oncoming traffic while trying to safely exit the roadway. 3. Has the problem been reproduced or confirmed by a dealer or independent service center? The issue was confirmed by a repair shop, which diagnosed the cause as a misfire due to a broken valve. I have service documentation of the diagnosis available. 4. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives, or others? The vehicle has not yet been inspected by the manufacturer or insurance representatives, but it was inspected by the servicing dealership and/or an independent mechanic who confirmed the valve failure. 5. Were there any warning lamps, messages, or other symptoms of the problem prior to the failure, and when did they first appear? Prior to the complete failure, the check engine light illuminated and the vehicle began running roughly (misfiring). These symptoms appeared very shortly before the breakdown, giving me no meaningful time to react before the engine stalled.

Filed Feb 8, 2024 · Acceleration, Engine · 95,000 miles · GA

The contact owns a 2018 Kia Sorento. The contact stated that while accelerating, there was an abnormal knocking sound coming from the vehicle. There were no warning lights illuminated. The vehicle was taken to the local dealer, where it was diagnosed that the knock sensor needed to be replaced. The vehicle was repaired, but the failure recurred. The mechanic completed a road test and indicated that the vehicle was working as designed. The vehicle was not diagnosed or repaired. The contact stated that while driving at 65 MPH, the vehicle was shuddering, shaking, and then lost motive power and stalled. The check engine warning light was illuminated. The contact used a code reader and retrieved DTC code: P1326 (Permanent go Relay Stuck On). The vehicle was taken to an independent mechanic, who cleared the codes but informed the contact that the failure would continue and recommended an engine replacement. The contact stated that while driving at 70 MPH, the check engine warning light illuminated. There was a thumping noise detected from the engine. The contact reduced the speed to 40 MPH. The vehicle began to hesitate, sputtered, and failed to accelerate. The contact used a code reader and retrieved DTC code: P0302 (Cylinder Misfire). The manufacturer was contacted, and opened a case. The failure mileage was approximately 95,000.