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All vehicle manufacturers—including those deemed the most reliable, such as Toyota—occasionally roll out a design flaw or manufacturing defect. These issues often become pattern failures that affect thousands of vehicles. 

Visit any repair facility across the country, and you’ll see service bays filled with vehicles afflicted by these well-known problems. Check for your vehicle’s make (or makes you’re in the market for) in our breakdown below—you just might avoid a breakdown of your own!

10 Pattern Failures From 10 Different Automakers

Every vehicle manufacturer has produced multiple design flaws and manufacturing defects over the years. Let’s take a look at some of the common, high-dollar pattern failures that your local mechanic is likely to see on a regular basis.  

Note: Although the failures on this list are common, they don’t always happen. Only a certain number of vehicles are actually affected by each design flaw or defect. 

General Motors Active Fuel Management Lifters

In 2007, General Motors (GM) introduced its so-called active fuel management (AFM) cylinder deactivation system in its small-block V8 engines. The technology uses special engine lifters to deactivate four of the eight cylinders under light-load driving conditions to improve fuel economy. 

With a traditional overhead valve (OHV) engine, the lifters, which ride on the engine’s camshaft lobes, continually operate a set of pushrods. The pushrods act on rocker arms that operate the engine’s valves to let air into the engine and exhaust gases out.

But the lifters in GM’s AFM-equipped engines operate a bit differently. The AFM lifters contain locking pins that are activated by oil pressure to allow the engine’s pushrods to remain stationary, thereby preventing the valves from opening. 

While the setup seems like a good idea on paper, it’s often problematic in real-world applications. The AFM lifters are known to collapse or suffer from failed rollers, frequently resulting in subsequent damage to the engine’s camshaft.

The failure results in a costly engine repair. In some cases, the engine may even need to be replaced if metal debris (from the damaged camshaft) has circulated throughout, causing additional damage. 

GM has issued several technical service bulletins (TSBs) regarding the AFM lifters and corresponding components. 

GM’s AFM lifters are known to collapse, frequently resulting in subsequent damage to the engine’s camshaft.

Hyundai Connecting Rod Bearings

All engines have a crankshaft, connecting rods, and pistons. When the spark plug ignites the air/fuel mixture inside of the engine’s cylinders, the piston and connecting rod assemblies force the crankshaft to turn, creating the rotational force needed to propel your car down the road. 

The connecting rods have bearings that support the piston assemblies and (with proper lubrication) allow the assemblies to rotate with very little friction. Although the bearings are small, they can cause big-time problems—such as catastrophic engine damage—when they fail. 

And that’s what’s happening to certain Hyundai vehicles. Select models from Hyundai (and its subsidiary, Kia) that are equipped with the brand’s 2.4L four-cylinder engine suffer from premature rod bearing failure. 

The problem almost always leads to extensive engine damage. In some cases, the connecting rod may even end up puncturing a hole in the side of the engine block. According to Hyundai, the root cause of the issue is debris from the manufacturing process that obstructs oil passages, resulting in a lack of lubrication to the rod bearings.  

Thankfully, the automaker has extended the warranty on affected vehicles. Also, a recall was issued to update the software on at-risk models so the engine computer can more easily detect a bad rod bearing.  

Select models from Hyundai equipped with the brand’s 2.4L four-cylinder engine suffer from premature rod bearing failure. 

Nissan Continuously Variable Transmissions

For the last decade or two, Nissan has been using continuously variable transmissions (CVTs) in most of its vehicles. Unlike traditional automatic transmissions, which use planetary gear sets to manipulate engine output, CVT transmissions rely on a steel belt and set of adjustable pulleys.

CVTs are supposed to improve fuel economy because they don’t need to switch gears like a traditional automatic. Nissan’s CVTs, however, are known for exhibiting a variety of problems, ranging from a “judder” sensation to overheating. 

The overheating issue is the biggest problem because it often forces the vehicle into a “limp” mode, resulting in a loss of power. Obviously, this is a potentially dangerous scenario that can put occupants at risk.

Nissan has agreed to extend the warranty on its CVTs found in select vehicle models.

Nissan’s CVTs are known for exhibiting a variety of problems, ranging from a “judder” sensation to overheating. 

Ford Dual-Clutch Automatic Transmissions

Ford’s 6-speed dual-clutch transmission (DCT)—known as the PowerShift or DPS6—is different from a traditional automatic. The DPS6 is essentially an automated manual transmission, with two input shafts driven by a computer-controlled dual-clutch system. 

The DPS6 is Ford’s attempt to combine the efficiency of a manual transmission with the convenience of a traditional automatic. Unfortunately, the concept execution failed—and many of the DPS6 transmissions found in the Ford Focus and Fiesta started having problems. 

Common issues with the DPS6 transmission include jerking, bucking, harsh engagement, and delayed acceleration. In some cases, the units have even been known to neutralize, leading to a potentially dangerous loss of power. 

To address these concerns, Ford has extended the warranty on the clutches and transmission control modules (TCMs) found in select DPS6-equipped models. 

Common issues with the DPS6 transmission include jerking, bucking, harsh engagement, and delayed acceleration.

Chrysler (Stellantis) Cylinder Head and Valve Train Issues

All engines have one or more cylinder heads that sit on top of the engine block. Cylinder heads house the valves, which let air into the engine and exhaust gases out.

With an overhead camshaft (OHC) engine, such as Chrysler’s Pentastar V6, the cylinder heads also house the camshafts and related components (e.g., lash adjusters and cam followers) that operate the valves. 

Despite receiving much praise for its advanced engineering, the Pentastar engine has a few common issues, one of which is leaking valves inside of the bank two cylinder head. Supposedly, a combination of low-quality fuel and certain driving conditions can cause the valves to leak, resulting in a loss of compression and poor engine performance. Chrysler extended the engine warranty on select models as a way of addressing the issue. 

Other common 3.6L engine problems include faulty camshaft followers (rocker arms) and/or lash adjusters (lifters). The cam followers suffer from worn needle bearings, while the lash adjusters are known to collapse. 

Either issue can result in costly damage to the engine’s camshafts. In some cases, if the problem is severe enough, additional damage to the engine may result from metal contamination. 

Chrysler has released a technical document, called a STAR case, that advises dealership technicians on how to address the concern.

Faulty camshaft followers (rocker arms) and/or lash adjusters (lifters) are common 3.6L engine problems.

Toyota Rusted Frames

Toyota has long been considered one of the most reliable vehicle brands on the road. But the automaker isn’t infallible, as some owners of Toyota trucks and SUVs have come to find out. 

Select Toyota Tacoma, Tundra, and Sequoia models located in the salt belt have been known to suffer from abnormally rusty frames. The common consensus is that the problem stems from improper anti-corrosion treatment at the factory. 

In 2016, Toyota settled a $3.4 billion class-action lawsuit regarding the issue. The automaker agreed to inspect affected vehicles and apply a corrosion-resistant compound to prevent further deterioration of the frame. 

Toyota also agreed to cover the cost of replacing the frame (up to $15,000) if needed. The coverage is good for up to 15 years after the vehicle’s manufacturing date.

Select Toyota Tacoma, Tundra, and Sequoia models located in the salt belt have been known to suffer from abnormally rusty frames.

Mazda Variable Valve Timing Components

These days, almost all new vehicles come with variable valve timing (VVT). The technology typically uses hydraulically operated camshaft actuators (also known as camshaft phasers) to adjust the position of the camshaft in relation to the crankshaft, thereby altering valve timing. The camshaft and crankshaft are kept in sync by a timing chain. 

Even though nearly all late-model vehicles have VVT actuators, the actuators in some Mazda vehicles tend to have an exceptionally high failure rate. CX-7, Mazda3, and Mazda6 models with the 2.3L turbocharged L3T engine built between 2006 and 2007 are the most prone to such problems. 

But Mazda’s timing component issues aren’t limited to the actuators. Select L3T-equipped vehicles also suffer from loose timing chains that can cause a rattling or knocking noise at lower RPMs. In some cases, the chains slapping around can lead to the engine having to be replaced. 

Mazda issued a warranty extension for the parts on select vehicles. The coverage, which has now expired, was good for seven years or 70,000 miles after the vehicle’s date of production.

Select Mazda vehicles suffer from loose timing chains that can cause a rattling or knocking noise at lower RPMs.

Honda Oil Dilution

In 2016, Honda released its 1.5L turbocharged L15B7 engine in the Honda Civic. The engine was a new route for Honda, as it featured both turbocharging and direct injection. 

Unfortunately, the technologically advanced engine is known to suffer from oil dilution problems that can affect long-term reliability. The issue stems from the engine’s direct fuel injection system, which sprays fuel directly into the combustion chamber. That fuel can sneak past the piston rings into the crankcase, where it mixes with engine oil.

In the case of the L15B7 engine, if the vehicle doesn’t reach operating temperature often enough (due to short trips or cold weather conditions), the fuel won’t burn off as it should. As a result, fuel-diluted oil is allowed to circulate throughout the engine. Because fuel doesn’t have the same lubricating properties as engine oil, the mixture can lead to accelerated wear of internal engine components. Some drivers also complain of engine performance problems that result from the dilution. 

To address these concerns, Honda issued a warranty extension on the parts affected by the dilution issue. The coverage, which applies to 2017 to 2018 CR-V and 2016 to 2018 Civic models, is good for 60,000 miles or 6 years from the original sale date. Honda also includes software updates and other tweaks that help mitigate the dilution problem.

Honda’s 1.5L turbocharged L15B7 is known to suffer from oil dilution problems that can affect long-term reliability.

BMW Variable Valve Timing and Variable Valve Lift Components

BMW refers to its variable valve timing system as VANOS, which stands for Variable Nockenwellen Steuerung—a term that translates to variable camshaft timing in English. Most BMW engines also have a variable valve lift system called Valvetronic.   

With the VANOS system, the engine computer operates solenoids to apply oil pressure to the camshaft actuators. The actuators then alter the angle of the camshaft, thereby changing engine valve timing. Meanwhile, the Valvetronic system relies on a servo motor to change the phase of an eccentric camshaft, which, in turn, modifies intake valve lift.  

Over the years, BMW has had a variety of problems with the components in its VANOS and Valvetronic systems. Issues range from faulty oil control solenoids to failed Valvetronic servo motors. 

In addition, certain BMW engines are known for experiencing timing chain stretch. The stretched chain has the potential to cause additional, not to mention expensive, internal engine damage. 

Over the years, BMW has had a variety of problems with the components in its VANOS and Valvetronic systems.

Subaru Head Gaskets

It’s no secret that Subaru engines—with their quirky boxer design—have had head gasket issues for decades. Later models equipped with the single overhead camshaft (SOHC) four-cylinder engine are especially susceptible to head gasket failures. 

Subaru engines have two head gaskets, each of which forms a seal between the engine block and a cylinder head. The head gaskets seal the cylinders to prevent compression leakage while also sealing the engine’s oil and coolant passages.

Depending on how a head gasket fails, the problem can lead to coolant leaks (internal or external), oil-coolant intermix, or compression loss. On Subaru engines, faulty head gaskets are also known to cause external oil leaks. 

Replacing a head gasket is a labor-intensive job, making it a costly repair to have done by a professional. On SOHC Subaru engines, the repair is essentially seen as unavoidable, and many owners budget for it as part of their routine maintenance regimen. 

It’s no secret that Subaru engines—with their quirky boxer design—have had head gasket issues for decades.

What Can You Do to Avoid Buying a Vehicle With Known Problems?

While it’s not always possible to avoid getting a vehicle with a design flaw or manufacturing defect, there are steps you can take to limit the likelihood of purchasing a problem vehicle. 

If you’re buying a brand-new car, it’s a good idea to research the reliability of previous model years. On the other hand, if you’re considering a used vehicle, you’ll want to explore the year (or the generation) of the model you plan to purchase. 

So, where should you begin your research? 

Consumer Reports and similar agencies only look at cars that are a few years old. As such, these resources aren’t the best for pinpointing common defects that can take several years to surface. Instead, you’ll want to consider looking into the following sources:

  • The National Highway Traffic Safety Administration (NHTSA) (https://www.nhtsa.gov/): NHTSA lists customer complaints, recalls, and investigations related to vehicles of all makes and models. 
  • Edmunds.com (https://www.edmunds.com/): Edmunds allows owners to post reviews of their vehicles. These reviews often shed light on a model’s common flaws. 
  • Under The Hood Show (https://www.underthehoodshow.com/): The experts on the Under The Hood Show field all types of questions from callers, including queries regarding pre-purchase information. 
  • Forums and Facebook Groups: There are forums and Facebook groups for vehicles of all makes and models. These resources can put you in touch with owners who have already experienced a certain vehicle’s flaws and defects. 
  • Local Experts: Local experts are often the best resource of all. If possible, find a seasoned automotive professional (mechanic, service advisor, etc.) who deals with the type of vehicle you’re thinking of purchasing. 

As machines designed by humans (who are, of course, prone to making mistakes), cars are bound to have flaws. The best way to avoid purchasing a problem model is to do some research beforehand.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. Read our full disclaimer here.

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