Active Fuel Management (AFM) system problems in your 2017 GMC Yukon can create ticking noises, misfires, oil consumption, and driveability concerns. The AFM system on the 5.3L and 6.2L V8 engines has documented issues affecting many GM truck and SUV owners.
Understanding AFM
The AFM system deactivates four cylinders (1, 4, 6, 7) during light load cruising to improve fuel economy. Specialized lifters lock to disable valve operation while fuel injection is cut. When functioning correctly, the transition is seamless.
Common AFM Problems
AFM lifter collapse creates ticking noise and misfires on deactivated cylinders. Oil consumption increases due to cylinder deactivation mechanics. Rough running during AFM activation affects drivability. Some owners report significant fuel savings don't justify the problems.
Lifter Failure Symptoms
A collapsed AFM lifter produces distinct ticking, often loudest on cold startup. Check engine lights with misfire codes on cylinders 1, 4, 6, or 7 develop. The ECM may disable AFM after detecting lifter problems, reducing symptoms temporarily.
Oil Consumption Connection
AFM operation allows oil to accumulate in deactivated cylinders, which burns when they reactivate. This contributes to oil consumption that many Yukon owners report. Disabling AFM often reduces consumption.