2017 Hyundai Sonata: misfire or rough idle

Filed Jun 30, 2026 · Engine · MD

Driving home from work on [XXX] (not a safe location)when my car lost power and engine light began to flash. I pulled off to the side of road and called my dad. He came with a code reader and said there was a code P1326. He cleared the code and car drove normally again. 2 days later it began to run rough. I was told about the engine recall so I called Hyundai corporate and told them this same story. I was advised to take to dealership and have the “rod bearings inspected” and shouldn’t matter that my dad cleared the code. The dealership(Massey Hyundai MD) said it had a burnt valve and not part of warranty. But never checked rod bearings. When I called corporate. They said nothing they could do. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Jun 6, 2026 · Engine, Suspension · PA

[XXX] [XXX] [XXX]; [XXX] [XXX] [XXX] Date: XXX To: the federal safety agency Office of Defects Investigation (ODI) Subject: Formal Safety Defect Complaint – 2017 Hyundai Sonata Theta II Engine Failure, Excessive Oil Consumption, Intake/Engine Component Failure and Safety Hazard Dear Sir or Madam: I am submitting this formal complaint and request for immediate investigation into the dangerous and ongoing mechanical failures involving my 2017 Hyundai Sonata equipped with the Theta II engine. I believe this vehicle contains a serious manufacturing and/or engineering defect that presents a substantial safety hazard to consumers. My vehicle has experienced a pattern of progressive mechanical failure beginning with abnormal and excessive oil consumption, which appears to be directly associated with malfunctioning engine airflow and intake-related components. Specifically, the lower engine airflow system and intake functionality appear defective, placing excessive strain on the intake manifold system and contributing to cascading engine failures. As a result of these failures, the vehicle has experienced: Severe and excessive oil burning/consumption Intake manifold malfunction and abnormal operating stress Suspected overheating and/or premature head gasket failure Ignition coil failure and electrical shorting/misfires Progressive engine deterioration rendering the vehicle unsafe and unreliable Increased risk of sudden engine shutdown, stalling, fire hazard, or catastrophic engine failure while operating The vehicle has become increasingly unreliable and inoperable due to these conditions. These failures raise significant concerns regarding public safety, especially given the known history of complaints and recalls associated with Hyundai Theta II engine defects. I am deeply concerned that this vehicle may reflect a broader pattern of defective manufacturing, insufficient quality control. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed May 13, 2026 · Engine · SC

The vehicle experienced repeated engine-related failures associated with the P1326 error code, which indicates a potential engine defect. The issue first occurred around February 2023 at approximately 51,500 miles, when a warning light appeared. The problem has recurred multiple times despite inspections and service attempts. In January 2024, a dealership performed a software update related to the P1326 code. Shortly after this update, the engine began consuming excessive oil (approximately 2 liters per 1,000 miles). The condition worsened over time, and the vehicle failed an oil consumption test conducted by a dealership. The issue was confirmed by an authorized dealership, which ultimately diagnosed the engine as failed and requiring replacement in May 2026 at approximately 99,000 miles. The problem has been reproducible, with the P1326 warning code appearing multiple times over the life of the vehicle. This condition creates a significant safety risk because the engine may lose power, misfire, or stall unexpectedly while driving, increasing the risk of a crash, especially at highway speeds or in traffic. The vehicle has already experienced engine misfire and severe performance issues. Warning indicators included the P1326 error code and check engine light, which first appeared in 2023 and recurred multiple times thereafter. The engine oil consumption issue developed after the 2024 service and continued to worsen. The failed engine is currently available for inspection upon request.

Filed Jan 2, 2026 · Engine · KS

Cylinders in the engine are misfiring causing car to shake. Pistons in the engine are having trouble keeping the air compressed so psi to continue to decrease causing the misfire.

Filed Sep 11, 2025 · Engine, Transmission · NV

What component or system failed or malfunctioned, and is it available for inspection upon request? The engine in my 2017 Hyundai Sonata Sport is defective. Oil pressure failed testing, oil contamination was found on the oil pressure sensor and connector, and the vehicle has experienced excessive oil issues. The engine is still in my possession and available for inspection upon request. How was your safety or the safety of others put at risk? The vehicle has gone into limp mode on the highway, which caused a sudden loss of power and created a dangerous situation in traffic. The car also shakes, misfires, and loses power unexpectedly, which could lead to stalling or loss of control at highway speeds. I do not feel safe driving the car. Has the problem been reproduced or confirmed by a dealer or independent service center? Yes. Multiple Hyundai dealerships have inspected the car. One confirmed low oil pressure and oil contamination at the sensor. Previous visits dismissed the oil warning and charged me for oil replacement instead of identifying the underlying defect. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? Yes. The vehicle has been inspected by Hyundai dealers multiple times. I also have two inspection reports from the same dealer just two weeks apart with contradictory findings the first showing no oil issue, the second confirming oil contamination and failed oil pressure. Were there any warning lamps, messages or other symptoms of the problem prior to the failure, and when did they first appear? Yes. The oil warning light and check engine light have both come on. The vehicle has gone into limp mode, and symptoms have included shaking, misfiring, rough idling, and loss of power. These issues began months ago and have continued despite repeated service visits.

Filed Aug 22, 2025 · Engine · IL

What component or system failed or malfunctioned, and is it available for inspection upon request?\n' + 'The engine in my 2017 Hyundai Sonata is defective. It burns oil excessively, fouls spark plugs and ignition coils, and causes continuous misfires. The engine is still in my possession and available for inspection.\n' + 'How was your safety or the safety of others put at risk?\n' + 'The engine misfires cause my car to shake violently while driving, lose power unexpectedly, and turn on the check engine light. This creates a risk of stalling or losing control while driving at highway speeds, endangering myself and others. I no longer feel safe driving the car.\n' + '\n' + 'Has the problem been reproduced or confirmed by a dealer or independent service center?\n' + 'Yes. Multiple independent mechanics have confirmed that the misfires and repeated spark plug/coil failures are caused by the engine itself, not just normal wear. Hyundai dealers acknowledged the excessive oil consumption and advised combustion cleanings, which did not resolve the issue.\n' + '\n' + 'Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others?\n' + 'Yes. The vehicle has been inspected by multiple Hyundai dealerships (including McGrath Hyundai) and independent service centers (Pep Boys, AAMCO, and others). All noted ongoing oil-related issues and repeated failures tied to the engine.\n' + '\n' + 'Were there any warning lamps, messages or other symptoms of the problem prior to the failure, and when did they first appear?\n' + 'Yes. The check engine light has come on repeatedly over the last two years. Symptoms include rough idling, heavy shaking, loss of power, and repeated ignition coil and spark plug failures (monthly or more often). The problem began within the first year of ownership and has persisted ever since despite repairs.

Filed Apr 1, 2025 · Engine · IL

This is the third time after 3 “repairs” that I have had my car at the dealer in less than a year. Car went into “limp” mode while driving down the highway causing car to stall and not go over 20 mph. First time they said it was a technical update needing done. Second time said low battery power causing issue so I purchased $300 battery from dealer and now showing cylinder 4 misfire and recommend replacing spark plugs and oil combustion testing due to having to add 3 quarts of oil every 230 miles due to excessive oil consumption. Dealer said this will not fix the issue however so why would I pay to have it done if it won’t fix the issue. Luckily these three incidents of engine power loss hasn’t caused me to have an accident but what If in 3 months and my engine loses power without warning for the 4th time in a year it dies cause an accident. I have a case open with Hyundai but am getting nowhere. I feel like a measly engine replacement would cost less than it will cost if this causes a major accident soon.

Filed Mar 13, 2025 · Engine · CA

I was driving on highway when all of sudden my vehicle began to shake hard and lose power, every time I stepped on the accelerator the check engine light came on, this happened on [XXX] in Los Baños, CA. My safety was at risk as all other traffic was going past me including semi trucks as I was trying to find a safe place to pull over out of harms way, as I was doing this the car shut off completely before I could even pull over. I had to get the vehicle towed to my local dealership where they had it for almost 3 weeks now, only diagnostic I’ve had back was that it has 2 misfires, one in cylinder 2 and the other in cylinder 4, and that it has no compression in cylinder 2. They said it isn’t covered under warranty which I believe should be looked into as I could of been serious hurt or lost my life due to this issues. I’ve had the vehicle serviced up to date since I’ve owed it and also noticed high oil consumption, not sure if this led to engine failure? The final diagnosis from Hyandai dealer is that engine is no good anymore and need replacement but it’s not covered under warranty. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Nov 23, 2024 · Engine, Seat belts · FL

The drivers seat belt does not engage. The engine has been burning oil, misfiring, and even after thousands in repairs was returned to me by the dealership with continued misfiring. When returning the car back to the dealer service center days later after Hurricane Helene, the car continued to misfire and became so overheated the engine light was flashing. Upon calling for a tow, I attempted to raise the hood for the driver to locate the car, but the hood was so hot it burned my hand. The engine was so hot, I believe it was about to catch fire and would have had I not been able to pull over so quickly. Had I been driving on the Interstate, I have no doubt this car would have been on fire within minutes.

Filed Nov 4, 2024 · Engine · TX

Excessive or consumption. Purchase a car three weeks later car started misfiring I was able to get the car to a mechanic shop. I was told that the car needed a tuneup, spark plugs and ignition call was changed mechanic noticed oil on top of the engine and advise me to get an engine gasket. Gasket was replaced 2 weeks later oil light comes on I added 5 quart of oil the light goes off I notified the mechanic again was able to get the car in the shop took mechanic replaced the gasket week later oil light was flickering took the car to have oil change. There was no oil in the car, three weeks later oil light flickering again checked oil it was empty I added five more quarts to the car and took the car back to the back the mechanic one he inspected it he informed me that the engine in the car for some reason consume a lot oil and that I should take the car to Hyundai dealership. I checked Hyundai recall for the oil consumption issue the car model I have is not apart of the recall. I could have lost my life when the car stalled due to oil is leaking where the spark plugs are located. Hyundai need to recall all 2013-2017 Hyundai sonata and Elentra

Filed Oct 24, 2024 · Engine · WI

In early June 2024 while driving 65 MPH vehicle started shaking, engine and oil light came on, losing power, noisy and only would go 50 MPH max. When destination reached, checked oil level (was low) added oil.Took the vehicle to auto repair shop. Review showed a misfire in cylinder #2 with plug oil fouled and recommended new engine. The car was taken to the Hyundai dealer who performed various diag. procedures via communicating with their Techline who ended up rejecting the request to replace the engine due to the milage (136K) being out of warranty. They would replace engine if the connecting rod bearings had wear or damage. Hyundai national consumer affairs contact given for the case refuses to listen to any information given and only states vehicle is out of warranty. Hyundai knows this engine has manufacturing issues causing them to wear out prematurely including excessive oil consumption. They should extend the warranty to at least 150K. Afraid to drive car as engine may suddenly stop or catch fire causing accident/injury to occupants. Please help!

Filed Feb 23, 2024 · Engine · KY

Had cruise control set for 75mph, and while traveling up hill, the car downshifted to maintain speed. After 10-15 seconds I noticed power loss and the check engine began to flash. Disengaged cruise control and pulled off onto the shoulder once I found a safe place to do so. As I was slowing down, there was a very noticeable misfire from the engine and was trying to stall out while still in motion. There was no knocking sound, nor was the car overheating. Once I was fully stopped, the car died and would not start back. Had the car towed back to my house. Replaced spark plugs because cylinders 2 and 4 were not firing properly. Also rotated coil packs around to see if they were failing. Cleared check engine codes but they immediately came back to misfires on cylinders 2 and 4. Did compression tests and found that cylinder 2 had 0psi and cylinder 4 had 20psi. Car was not low on oil and no other warning lamps were on.