Manufacturing Problems with the Theta II Engine Cause Knocking, Seizing, and Oil Sludge Buildup

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The Theta II engine with a more appropriate logo

The Theta II is a gasoline direct injection (GDI) engine that is well known for a lot of things and none of them are good. Bearing failure, metal debris riding on contaminated oil, piston ring defects, siezing, knocking, crying. I'm not done yet. Should I go on? Ok...

Then there's the excessive oil consumption, engine knocking, and who could forget that the whole darn thing might just catch on fire.

Which Cars Use the Theta II Engine?

A lot of Hyundai and Kia vehicles have the Theta II engine, but the one installed in the non-turbocharged 2011 and 2012 Sonata is a special blend of awful.

"Add another one to the list! While out of town yesterday, my 2011 Hyundai Sonata just stopped running in the middle of the highway. No warning lights, nothing, engine just stops running. My oil has been changed every 3000 miles. There has been no oil leaks, nothing, and it just stops running!" --- 2011 Sonata Owner

The cars all come with Hyundai's limited warranty which ever-so-conveniently expires just before the engine problems start popping up. And when looking for help on the ~$5,400 in repairs, it's just not there.

Manufacturing Problems

It took a long time, but Hyundai eventually admitted that metallic debris might have been left around the engine crankshaft during manufacturing. That can cause hell on your engine when it comes to oil flow.

Interestingly, the 2011 Sonata was the first to be built inside Hyundai's Alabama engine factory. The automaker says a "mechanical de-burring" process was used to remove any metallic debris from the engines. The de-burring didn't dework.

In April 2012, Hyundai changed the process to a high pressure "wet blast" for the 2013 model year.

Hyundai Recalls Some Theta II Engines for Fires

In September 2015, Hyundai recalled 470,000 Sonatas to prevent engine failures and fires. The 2011 and 2012 Sonatas all had 2-liter or 2.4-liter gasoline direct injection (GDI) engines.

Hyundai set up a site where owners can figure out if they're covered by the recall.

For a long time Hyundai was pretty emphatic there weren't any problems with the Theta II. Additionally, their argument against a recall was even if something went wrong the owner would be notified by a warning light before the engine take an early retirement.

NHTSA didn't see it that way. The agency was concerned that the engine could fail on the highway, leaving owners high and dry. That alone was enough of a safety threat to warrant a recall.

Extended Warranty

As part of the recall, Hyundai agreed to increase the warranty for the engine short block to 10 years/120,000 miles for the affected cars. If you've already had repairs done to your engine, contact Hyundai customer service at 855-671-3059 about a possible reimbursement.

Visit for more information about the recall.

A Former Engineer Spills the Theta II Beans

A former Hyundai engineer told the National Highway Traffic Safety Administration (NHTSA) that Hyundai was well aware of the Theta II problems, even as they denied it publicly and pushed against a recall.

There's a lot of fail points

The engineer, Kim Kwang-ho, was a Hyundai employee for 25 years. After his whistleblowing he was hauled in front of Hyundai's disciplinary committee and accused of leaking secret corporate information in August 2016.

Theta II Class Action Lawsuits and Settlement

In May 2015, Chimicles & Tikellis LLP – a leading national class action law firm – filed a class-action engine lawsuit against Hyundai. Their goal was simple:

"Recover the money [their clients] have lost, and obtaining the relief to which they are entitled."

Hyundai's Change of Heart

After a year in court, Hyundai had a change of heart and reached a proposed settlement:

"The proposed settlement has Hyundai reimbursing Sonata owners who paid for engine block repairs or replacements within 10 years and under 120,000 miles of the car's original sale or lease. The proposed agreement also includes expenses related to towing or rental cars needed due to the defective engines."

And it gets better.

While the original lawsuit only mentioned the 2011 and 2012 model years, the proposed settlement would cover any 2011-2014 Sonata in the U.S. with the Theta II 2-liter or 2.4-liter gasoline direct injection engines.

Is Kia Next?

In June 2016, a Kia Theta engine lawsuit was filed for owners of the 2011-2014 Optima, Sportage, and the 2012-2014 Kia Sorento.

Like the Hyundai lawsuit, the Kia version targets 2-liter and 2.4-liter GDI engines. The lawsuit claims these engines contain defects that restrict oil flow through the connecting rod bearings as well as other parts of the engine.

Original image of Theta II engine from wikipedia

Lawsuits Regarding This Problem

Lawsuits about this problem have already been filed in court. Many times these are class-action suits that look to cover a group of owners in a particular area. Click on the lawsuit for more information and to see if you're eligible to receive any potential settlements.

  • Thornhill, et al., v. Hyundai Motor Company, et al.

    1. Case Filed

      A Hyundai and Kia engine lawsuit alleges several models are equipped with defective gasoline direct injection (GDI) and multipoint fuel injection (MPI) engines which may catch fire.

    Class Vehicles
    • 2012 Santa Fe
    • 2011-2013 Sonata Hybrid
    • 2016 Sonata Hybrid
    • 2015-2016 Veloster
  • Elizabeth Mendoza vs. Hyundai Motor Company, LTD, Hyundai Motor America, Inc

    1. Case Filed

      A Hyundai Sonata engine failure lawsuit accuses Hyundai of manufacturing defective engines in model year 2011-2012 Sonatas. The plaintiff alleges Hyundai knew when the connecting rod bearings start to fail, metal debris from the bearings is sent throughout the engine through contaminated engine oil.

    Class Vehicles
    • 2011-2012 Sonata

Generations Where This Problem Has Been Reported

This problem has popped up in the following Hyundai generations.

Most years within a generation share the same parts and manufacturing process. You can also expect them to share the same problems. So while it may not be a problem in every year yet, it's worth looking out for.

Further Reading

A timeline of stories related to this problem. We try to boil these stories down to the most important bits so you can quickly see where things stand. Interested in getting these stories in an email? Signup for free email alerts for your vehicle over at

  1. Another owner has sued Hyundai and Kia for knowingly equipping vehicles with defective Theta II engines.

    Proving once again that when it comes to engines that catch on fire, people generally aren't fans. The automakers have settled similar lawsuits and issued recalls for these clunkers, but the plaintiff suggests not all affected vehicles were included.

    About the lawsuit

    • These gasoline direct injection (GDI) engines are plagued with problems. From bearing failure, to connecting rod knocks, to oil consumption, and yes – engine infernos.
    • The plaintiff bought their car used and shortly after learned that the car needed a new short block to the tune of $7,000. The work also took 6 months because there're a backorder on parts.
    • In December Hyundai recalled 128,000 vehicles over concerns they could catch on fire. But the lawsuit wants more coverage for the 2012 Santa Fe
      2011-2013, 2016 Sonata Hybrid, and 2015-2016 Veloster.
    keep reading article "Lawsuit Says Not Enough Vehicles Were Covered in the Theta II Recalls"
  2. Hyundai is recalling nearly 100,000 engines with fuel tubes that were misaligned, improperly tightened, or otherwise damaged during installation.

    This lets gas can spray out onto hot surfaces and is the **perfect recipe for engine fires. It gets worse.

    This was supposed to be Hyundai’s opportunity to right the wrongs of their gasoline direct injection engines with massive oil flow problems. Those engines were notorious for knocking, seizing, and were eventually recalled in multiple campaigns. These were the replacements and now because of an installation snafu they’re catching on fire.…

    keep reading article "Hyundai Can't Even Stop Their Replacement Engines From Catching on Fire"
  3. What are the odds that your car will set itself on fire without ever being involved in a collision?

    Much higher than you’d think, especially if you’re one of these 3 million Hyundai and Kia owners.

    The Center for Auto Safety (CAS) has put together a list of vehicles that they say should be taken off the road until a pending government investigation ends with a comprehensive recall.

    CAS says Kia and Hyundai have done nothing but provide empty statements about working directly with vehicle owners who report fires. In addition, both automakers seem to be waiting for NHTSA to conclude its investigation to determine if additional actions should be taken.

    keep reading article "Are 3 Million Hyundai and Kia Cars Too Dangerous to Drive?"
  4. Federal investigators are taking a look at Hyundai’s handling of Theta II engine recalls to make sure there’s no funny business going on.

    NHTSA says it took action to "investigate both the timeliness and scope of Hyundai's Theta II engine recalls, and Hyundai's compliance with reporting requirements.

    Timely and compliant? Not if you ask this lawsuit. Or this former Hyundai engineer. To date, nearly 1.7 million Hyundai and Kia vehicles have been recalled.

    keep reading article "Safety Regulators Are Investigating Hyundai’s Handling of Theta II Recalls"
  5. 572,000 Sonata and Santa Fe Sport vehicles are being recalled because the Theta II engines can seize at any moment.

    Hyundai says machining errors occurred when the engines were built and those errors can cause the engine bearings to wear out early. Those prematurely worn bearings will cause the engine to lock up, something a dealer will need to fix by replacing the engine short block.

    Hyundai admits that two errors made during manufacturing are responsible for this problem.…

    keep reading article "More Stalling Theta II Engines Will be Replaced in the 2013-2014 Sonata and Santa Fe Sport"
  6. A Theta II engine settlement for Mendoza v. Hyundai Motor Co. Ltd., et al. has been approved by the court.

    A Hyundai Sonata class-action lawsuit will receive final approval after U.S. District Judge Beth Labson Freeman said she sees no problem with the settlement terms and believes the agreement is excellent for Sonata owners.

    Hyundai was accused of concealing defects with their Theta II GDI engines, and the settlement helps owners of the 2011-2014 Sonata with either the 2L or 2.4L variant.…

    keep reading article "Sonata Theta-II Lawsuit Settlement Gets the Green Light"
  7. Hyundai is recalling 470k 2011-2012 Sonatas with 2.0L or 2.4L Theta II engines for knocking, stalling, and potential engine fires.

    The “gasoline direct” engines are the first batch to come from Hyundai’s new engine factory in Alabama. If they keep this up, it might be their last too.

    Hyundai says manufacturing problems could have left metallic debris around the engine crankshaft and cause problems with oil flow. The pieces of metal could interfere with the oil flow through the connecting rod bearings and damage the connecting rod.”…

    keep reading article "Left Over Metal Shavings Force Recall of 470,000 Theta II Engines"
  8. Contaminated oil is carrying metal shavings on a not-so-joyful ride through the Theta II engine leading to knocks, stalls, and eventual failures according to a recent class-action filed by a Sonata owner in California.

    [The plaintiff]_ brought [her] Sonata to a dealership and was told a piston had blown out. Mendoza asked for her car to be repaired under warranty, but the dealership refused to make the repairs. However, the dealer said the engine could be replaced for $4,500. Mendoza said no and took the Sonata to a mechanic and had the engine replaced at a cost of $3,000.

    The plaintiff says she followed Hyundai’s recommended maintenance intervals and there was no reason her engine should have seized, you know other than the whole “doomed from the start” theory.…

    keep reading article "California Class-Action Says The Sonata’a Theta II Engine Knocks Before Failing"

What Owners Say About This Problem

This was the third engine failure for this vehicle and the last. I am not going to go through this again and will slowly drive the vehicle to an auto wrecking site and give it to them.

2011 Sonata Owner

OK, Now What?

Maybe you've experienced this problem. Maybe you're concerned you will soon. Whatever the reason, here's a handful of things you can do to make sure it gets the attention it deserves.

  1. File Your Complaint is a free site dedicated to uncovering problem trends and informing owners about potential issues with their cars. Major class action law firms use this data when researching cases.

    Add a Complaint
  2. Notify CAS

    The Center for Auto Safety (CAS) is a pro-consumer organization that researches auto safety issues & often compels the US government to do the right thing through lobbying & lawsuits.

    Notify The CAS
  3. Report a Safety Concern

    The National Highway Traffic Safety Administration (NHTSA) is the US agency with the authority to conduct vehicle defect investigations & force recalls. Their focus is on safety-related issues.

    Report to NHTSA