How do I know if I have Active Fuel Management?
Active Fuel Management (AFM), also known as Displacement on Demand or Cylinder Deactivation, is a technology used in some vehicles to improve fuel efficiency. If your vehicle has this feature, it can automatically shut off some of the engine's cylinders when they are not needed, such as during light-load driving conditions. Here's how you can determine if your vehicle has Active Fuel Management.
Check Your Vehicle's Specifications
The easiest way to find out if your vehicle has Active Fuel Management is to check the manufacturer's specifications or your owner's manual. Look for terms like "Active Fuel Management," "Displacement on Demand," or "Cylinder Deactivation" in the engine or powertrain details.
Look for Indicators on the Dashboard
Many vehicles with Active Fuel Management will have an indicator light on the dashboard that illuminates when the system is active and deactivating cylinders. This light may be labeled "AFM," "Eco," or something similar. Check your dashboard for any such indicators.
Listen for Engine Noise Changes
When Active Fuel Management is engaged, you may notice a subtle change in the engine's sound. The engine may sound slightly quieter or smoother when running on fewer cylinders. Pay attention to any noticeable differences in engine noise during your driving.
Monitor Fuel Economy
If your vehicle has Active Fuel Management, you may notice an improvement in your fuel economy, especially during highway driving or other light-load conditions. Compare your fuel efficiency before and after the system is engaged to see if there is a noticeable difference.
Consult a Mechanic
If you're still unsure whether your vehicle has Active Fuel Management, consult a qualified mechanic. They can use diagnostic tools to determine if the system is present and functioning correctly.
Knowing whether your vehicle has Active Fuel Management can help you understand how your engine operates and optimize your driving habits to take advantage of the fuel-saving benefits of this technology.
What engines have Active Fuel Management?
GM used the Active Fuel Management technology on a range of engines including with the GM Small Block Gen IV engine family, first-generation GM EcoTec3 engine family, second-generation GM High-Feature V6 DOHC engine family, and first-generation High-Feature V8 DOHC engine family.
How do you tell if you have Active Fuel Management?
Specific visual cues and components under the hood can indicate the presence of AFM technology. Knowing what to look for lets you quickly identify if your vehicle is equipped with this fuel-saving system. These indicators include engine cover markings, unique solenoids, and specific valve cover designs, among others.
What are the symptoms of bad Active Fuel Management?
The symptoms of a cam or lifter failure usually involve a chirping, ticking, squealing or squeaking sound accompanied by a Check Engine light and engine misfire codes stored in memory. The misfire condition may not be evident to the vehicle operator.
Which GM engines do not have an AFM?
The LM2 Duramax 3.0L turbo-diesel, the L8T 6.6L V8, and the LS3 have neither AFM nor the latest version, called DFM (Dynamic Fuel Management). In addition, some 5.3L V8s from 2021 and 2022 don't include either fuel-saving system due to semi-conductor shortages manufacturers were dealing with during that time.
