[Z15]

i Have a 2021 Sierra Denali 6.2L (built Aug 2020) and it has DFM. It was NEVER an option, came standard on every V8 in the 1500 series.

I bet you really have it (dealer wrong) because it was not till late 2021 early 2022 models that the chip shortage occurred. From my understanding, it was only certain 5.3L engines (no 6.2L) that came w/o DFM active even though the engines were still built with all the mechanical components, just that the CPU were non-DFM capable (built w/o the chips).

BTW, according to an article I read DFM requires 100's of chips (size of pinheads) to work, not just one as many would assume.

 

[Z15]

fyi...People working in the dealerships are not always the most knowledgeable people to answer these questions. My dealer for instance, which is a good sized dealer, has had a complete change over of the 2 service advisors in the last 6-months. What they did is fill those positions with former salesman who are not cutting it. I even seen one of them arriving at work driving a Toyota so you can bet he probably can't even spell GMC.

Two weeks ago we reported that GM would stop producing some of its 5.3L engines with active fuel management(AFM) and dynamic fuel management (DFM) due to the worldwide chip shortage. Today we have more information on exactly how those engines will be configured to accomplish that goal.

The company has released an updated Technical Service Bulletin (#21-NA-078) that sheds further light on exactly these AFM/DFM-less engines will be built and which parts are being removed.

It turns out the changes are entirely electrical. The ECM is being swapped while all of the hardware components of AFM/DFM will still be present inside the engines.

The changes only apply to 5.3L (L82/L84) engines equipped with 6-speed (MYC) and 8-speed(MQE) transmissions. Chevrolet Silverado and GMC Sierra pickups shipped with AFM/DFM deactivated will carry the RPO code YK9.

According to GM:

• Internal components related to AFM or DFM function will be present in engines; wiring, connectors, and fuses will be present in vehicles with RPO YK9. The ECM will not be capable of activating the cylinder deactivation technology.
• When diagnosing and repairing concerns with base engine or electrical function which may be related to AFM or DFM related hardware; utilize appropriate diagnostics within SI and replace any needed components as directed by the Electronic Parts Catalog; no changes will occur to AFM or DFM related components.
• Important: Any truck designated with RPO YK9 CANNOT be reprogrammed and changed to “Turn on” the AFM/DFM functionality.