5 Common GM 6.2 Gas Engine Problems with Symptoms and Solutions

The General Motors (GM) 6.2 gas engine is a powerful and widely used engine in various vehicles, known for its reliability and performance. Like any mechanical system, it is not immune to issues that can arise over time. In this article, we will explore five common GM 6.2 gas engine problems that owners may encounter, along with their symptoms and possible solutions.

From rough idling to reduced power output, these problems can significantly impact the overall performance and longevity of the engine if left unaddressed. Understanding the signs of these issues is crucial for timely diagnosis and repair, ultimately prolonging the life of your GM 6.2 gas engine.

GM 6.2 Gas Engine Problems | 5 Problems, Symptoms and Solutions

GM 6.2L gas engines have the following 5 common problems:

  1. AFM Issues
  2. Carbon Buildup
  3. Intake manifold gasket leaks
  4. Exhaust manifold bolt failure
  5. Low oil pressure issue

AFM Issues:

Many owners of vehicles equipped with this engine have reported issues related to the Active Fuel Management (AFM) system. The AFM is designed to improve fuel efficiency by deactivating half of the engine’s cylinders during low-demand situations, such as cruising on the highway. It has been plagued with problems that can lead to significant performance and reliability issues.

Some drivers have noticed that their vehicles require frequent oil top-ups between scheduled maintenance intervals. This can be attributed to a faulty AFM system, which may cause increased cylinder wear and oil consumption.

Symptoms of AFM Issue

  • Reduced fuel economy
  • Engine misfires
  • Engine vibration


GM 6.2 Gas Engine Problems

Solutions are available for GM 6.2 gas engine problems, specifically related to AFM issues. One option is disabling the AFM system through a custom tune or performance module installation. This will prevent the engine from entering into cylinder deactivation mode and alleviate any associated problems. It’s important to note that disabling AFM may negatively impact fuel efficiency in certain driving conditions.

Carbon Buildup:

Carbon buildup occurs when unburned fuel residues accumulate on various components of the engine over time. The most common areas affected are the intake valves and combustion chambers. As this carbon layer thickens, it restricts airflow and disrupts the proper functioning of these crucial parts. Consequently, drivers may experience reduced acceleration, poor throttle response, and even misfires or stalling at idle speeds.


  • Slow acceleration
  • Poor idling
  • Engine misfires
  • Reduced performance
  • Rich air-to-fuel ratios


Use specialized fuel additives that help break down the carbon deposits and clean out the combustion chamber. These additives can be poured directly into the fuel tank during regular fill-ups and work by dissolving the built-up deposits over time.

Intake Manifold Gasket Leaks:

A prevalent problem owners may encounter with this engine is intake manifold gasket leaks, particularly after driving approximately 80,000 miles. Gasket is also responsible for a vehicle to blow white smoke.

The intake manifold gasket is crucial in sealing the intake manifold to the engine block, ensuring proper air and fuel mixture delivery to the cylinders. Over time and extensive use, the gasket can deteriorate or develop cracks due to various factors such as heat cycles and engine vibrations. This can result in internal coolant leakage or air leaks that disrupt combustion and compromise engine performance.


  • Engine overheating
  • Coolant leaking
  • Engine starting issues
  • Check engine light


Solution for dealing with intake manifold gasket leaks in the GM 6.2 gas engine is to replace the faulty gasket. This can be done by a professional mechanic or experienced car enthusiast, but it does come at a cost. On average, the replacement cost for an intake manifold gasket in this engine ranges between $550 and $615. While this may seem like a significant expense, it is crucial to address the issue promptly to prevent further damage and ensure optimal engine performance.

Exhaust Manifold Bolt Failure:

This problem has been reported across various GM models equipped with the 6.2-liter V8 gas engine, causing frustration and expensive repairs for vehicle owners.

The exhaust manifold bolts are crucial in adequately functioning the engine’s exhaust system by securing the manifold to the cylinder head. Over time, these bolts can rust due to exposure to heat and environmental factors, ultimately leading to failure. If left unaddressed, this can result in exhaust leaks, decreased performance, excessive noise, and even potentially dangerous situations.


  • Check engine light
  • Exhaust leaks
  • Engine misfires
  • Reduced engine power
  • Rough idle


There is a simple solution to this problem – replacing the faulty bolts at a professional workshop.

Low Oil Pressure Issue

GM 6.2 Gas Engine Problems

Low oil pressure can lead to engine damage, reduced power output, and even complete engine failure if not addressed promptly.
The cause of low oil pressure in the GM 6.2 gas engine is a faulty oil pump. The oil pump is responsible for circulating the lubricating oil throughout the engine, ensuring that all moving parts are adequately lubricated and cooled. If the pump fails or becomes clogged with debris, it can result in insufficient oil flow, leading to decreased pressure within the system. Another potential cause of low oil pressure is an internal leak within the engine block or cylinder heads.


  • Engine misfires
  • Low oil pressure indicator light on
  • Engine knocking or noise
  • Rough idle
  • Overheating


A straightforward solution has been identified – replacing the O-ring. This small yet crucial component is vital in maintaining proper oil pressure levels within the engine.


With proper maintenance, the GM 6.2L gasoline engine proves dependable in performance, power output, and durability. It can last over 250,000 miles or 10 to 20 years. But still, some GM 6.2 gas engine problems should be resolved. Despite its numerous advantages, the engine is susceptible to specific common issues. To prevent these problems, it is crucial to maintain the machine regularly and have it professionally inspected annually.


Are Duramax 3.0 and 6.2 same?

No, the Duramax 3.0 and 6.2 are not the same engines. The Duramax 3.0 is a smaller, inline-six diesel engine that was introduced by General Motors in 2019. It is designed for use in light-duty trucks and offers a balance of power and fuel efficiency.

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