The Vortec engine family was plagued by problems with oil consumption and AFM, leading to GM developing the new EcoTec3 engine family in 2014.
However, the EcoTec3 engine family, including the 5.3L engine still suffer from AFM related problems. Additionally, the 5.3L engine specifically has common problems with carbon build-up, fuel injector failure, 4WD, fuel level sensors, and lifters caused by AFM.
This guide is going to dig into each of the common problems of the 5.3L EcoTec3 and discuss overall engine reliability.
Engine Variations & Overall Reliability
The 5.3L EcoTec3 engine is a small-block V8 engine, similar to its Vortec 5300 predecessor. The engine was produced in 4 different variations, the L83, L8B, L82, and L84.
- 2014-2019 Chevy Silverado and GMC Sierra
- 2014-Present Chevy Tahoe and GMC Yukon
- 2014-Present Chevy Suburban and GMC Yukon XL
- 2016-2018 Silverado and Sierra 1500
- L82 & L84
- 2019+ Silverado and Sierra 1500
These engines are all considered to be reliable. They don’t tend to suffer from any catastrophic problems but they do frequently have issues with lifter failure caused by active fuel management. Additionally, the fuel injectors fail frequently which is another common problem.
The lifter and AFM issue will typically result in problems by the time you reach the 200,000 mile mark – but there are some cases of engines lasting way longer or even way shorter.
Chevy EcoTec3 5.3L Engine Problems
- Carbon build-up
- Fuel injector failure
- 4WD transfer case sensor failure
- Fuel level sensor failure
- Active fuel management – is it still a problem?
1. Carbon Build-up
One key difference between the Vortec and EcoTec3 engine families is fueling. While the Vortec engines used port-injection the EcoTec3 engines were built with direct fuel injection. With port-injection, gasoline is injected into the intake ports where it then travels to the cylinders which helps clean any gunk out of the intake ports.
On direct injection engines, the fuel is injected directly into the cylinders, completely bypassing the intake ports. Because the intake ports are bypassed, there is no high-pressure fuel flow to keep them clean and gunk free. This results in a build-up of gunk or sludge as a byproduct of oil and fuel burn that lines the intake ports.
Symptoms of Carbon Buildup
- Rough idling, stuttering at idle
- Decreased power and shaky acceleration
- Engine misfires
- Slightly lean AFR ratios
You will probably start to notice some carbon buildup effects around the 70,000-80,000 mile range. The only true way to fix this is to regularly clean the intake ports by removing the manifold and walnut blasting or pipe cleaning the valves.
2. Fuel Injector Failure
Due to the high heat and extreme pressure, fuel injectors usually wear out over time. They can become gunked up, begin leaking, loose pressure, or simply completely fail. On the 5.3L engine, the injectors are mostly known to completely fail.
When an injector fails, it either fails in an open or a closed position. When an injector fails open it sprays too much gasoline into the engine, and vice versa when it fails closed. On these engines, they commonly fail closed which results in no gasoline entering the cylinder with the failed injector.
Each cylinder has its own injector, but they do at least tend to fail one at a time, rather than all at once. Bad injectors will certainly limit the driveability of your car and will have some very notice performance effects.
Fuel Injector Failure Symptoms
- Cylinder misfires (most common sign)
- Rough idling, poor acceleration, loss of power
- Check engine light with engine misfire codes
- Air-to-fuel ratios are either running rich or lean
The easiest way to tell that you have an injector problem is through the check engine light and engine codes for misfires. You will get cylinder-specific misfire codes which will point you in the direction of the bad injector. It’s worth noting that bad spark plugs and ignition coils can also cause engine misfires, so you might want to check these things prior to replacing an injector as injectors tend to be more expensive and difficult to replace.
3. 4WD Transfer Case Sensor Failure
Transfer case issues on the 4×4 Chevy’s and GMC’s go back to the 1990’s. Unfortunately, transfer case sensor failure has been reportedly somewhat commonly on all cars with the EcoTec3 engine. While this sensor isn’t necessarily engine related, it’s common enough in 2014-present models that it’s worth mentioning.
The transfer case is responsible for transferring powering from the engine to the front and rear wheels, through the driveshaft. On vehicles where you have 4×4 and rear-wheel drive options, there is a transfer case sensor that is responsible for controlling whether the truck is in 2-wheel or 4-wheel drive mode. When the sensor fails, the truck can get stuck in or out of 4×4 mode. Additionally, it is common for the truck to shift itself in and out of 4×4 without your control. This can lead to difficulty shifting gears, and noises from the transmission of the truck.
- Truck is stuck in 4×4, or won’t go into 4×4
- 4WD Service light appears on dash
- Noisy shifting gears, or difficult to shift gears
- 4WD light flashes on and off intermittently
Fortunately, the repair here is as simple as replacing the transfer case sensor which is a rather inexpensive job. We recommend fixing this issue when it arises as continuing to drive can cause drivetrain issues if your car is frequently trying to switch in and out of 4WD while it’s moving.
4. Fuel Pump Failure
The 5.3 EcoTec3 has both a low-pressure fuel pump and a high-pressure fuel pump, or LPFP and HPFP. High-pressure fuel pumps are common failure points on virtually all direct injection engines.
These high-pressure pumps are also extremely stressed due to the heat and pressure they operate under. Over time it is common for the internal components to wear out and cause the pump to fail. Likelihood of HPFP failure is increased on trucks that are tuned, driven aggressively, or have performance modifications. The more horsepower your truck makes, the more fuel it needs to feed the engine. Therefore, the harder the HPFP has to work to deliver that fuel.
Fuel Pump Failure Symptoms
- Long crank times
- Engine won’t start
- Engine malfunction light appears or service engine light
- Reduced power and performance
5. Active Fuel Management Problems
One of the biggest issues with the 5.3L Vortec, and really all Cortec engines for that matter, was excessive oil consumption caused by the active fuel management system. The AFM system issues are one of the big reasons that GM transitioned to the new EcoTec3 engine family. AFM, also known as cylinder deactivation is where the engine shuts off 50% of the cylinders under certain driving conditions in order to improve fuel efficiency.
On the 5.3L V8, 4 of the cylinders are shut off, essentially making your truck a V4. The AFM system is known to cause excessive oil consumption issues. In addition to excessive oil consumption, the AFM can also cause the lifters to fail on the EcoTec3 engines, which is a rather expensive fix. AFM is good for maybe 10-15% improved fuel economy, but really isn’t worth it for all the potential problems it can create.
Is AFM still an issue?
While everyone hoped the EcoTec3 engine would fix the AFM issues, they still appear to be common. However, I would note that they appear to be somewhat less common that they were on the previous Gen III and IV vortec engines. Although this might be due to the fact that these engines are newer and less people are reporting problems as their cars likely still have factory warranty. The short answer is yes, the EcoTec3 engines still have AFM issues.
Check out our full guide on disabling or deleting AFM.