GMC Sierra 1500 2007-2018 4.3L/5.3L/6.0L/6.2L V6/V8 AFM/DFM Disabler

This AFM/DFM disabler plugs into the OBD-II port of the 2007–2018 GMC Sierra 1500. Its job is to keep the engine running on all cylinders instead of dropping into the reduced-cylinder mode that GM's Active Fuel Management uses at light load. It does not rewrite engine software, and removal takes seconds: unplug the module and the vehicle is back to stock behavior.

Fitment by year and engine

Listed applications, each a 100% fitment match:

• 2007–2009 GMC Sierra 1500: 5.3L V8 / 6.0L V8
• 2010–2013 GMC Sierra 1500: 5.3L V8 / 6.0L V8 / 6.2L V8
• 2014 GMC Sierra 1500: 4.3L V6 / 5.3L V8 / 6.0L V8 / 6.2L V8
• 2015–2017 GMC Sierra 1500: 4.3L V6 / 5.3L V8 / 6.2L V8
• 2018 GMC Sierra 1500: 4.3L V6 / 5.3L V8

For reference, these are the AFM-equipped GM engine codes that match the years and displacements above:

• LY5 (5.3L, 2007–2009, VIN 8th digit "J")
• LC9 (5.3L, 2007–2011, VIN 8th digit "3")
• LMG (5.3L, 2007–2014, VIN 8th digit "0")
• L76 (6.0L, 2007–2009, VIN 8th digit "Y")
• LFA (6.0L, 2008–2009, VIN 8th digit "5")
• LZ1 (6.0L, 2010–2013, VIN 8th digit "J")
• LV3 (4.3L, 2014–2018)
• L83 (5.3L, 2014–2018, VIN 8th digit "C")
• L86 (6.2L, 2014–2018, VIN 8th digit "J")

In the same trucks and SUVs, GM also built V8s without AFM, for example the 5.3L LH9 (2010–2012 trucks, VIN code P), the 6.0L LY6 and L96 and the 6.2L L9H. Those engines never deactivate cylinders, so the module has nothing to manage on them. Check your code against both lists before you buy.

If your engine code is not in this list, email the VIN to support before ordering so we can confirm the application.

What AFM does on these engines

GM's Active Fuel Management turns a V8 into a V4 at light load by deactivating cylinders 1, 7, 6 and 4. Solenoids route oil pressure to the lifters on those cylinders, which collapse and stop opening the valves. Fuel to those cylinders is cut at the same time. Press the throttle harder and the system brings all eight back.

GM's 4.3L V6 (RPO LV3) uses the same idea on two cylinders: cylinders 3 and 6 are deactivated at light load, so the engine runs on four. On V8s, AFM drops cylinders 1, 7, 6 and 4. In both cases oil-pressure solenoids switch special lifters into a collapsed state and fuel to those cylinders is cut.

For the 2019 redesign of the Silverado 1500 and Sierra 1500, GM introduced Dynamic Fuel Management on the 5.3L L84 and 6.2L L87, which can run on 17 different cylinder patterns. That is a different system from the AFM covered by this listing.

Engine care

Disabling cylinder deactivation does not replace normal maintenance. Use the oil grade and change interval GM lists for your engine, watch the oil level between changes, and repair leaks promptly. The valvetrain on these engines depends on clean oil at proper pressure in every mode.

Reasons to keep all cylinders running

Many drivers would rather have predictable response than the small economy gain from running on fewer cylinders, especially when towing, hauling or driving in hills. Keeping AFM off removes the mode changes entirely. It does not add horsepower, and it is not a fix for an engine that already has lifter or oil-consumption problems.

Check the engine first

This module prevents mode switching. It does not repair anything. If the engine already has a ticking lifter, misfire codes, low oil pressure or high oil consumption, have it diagnosed before relying on the module. Those symptoms need a mechanical repair, and keeping AFM off will not reverse damage that has already happened.

What changes when you drive

Drive at a steady cruise on a light throttle, where AFM used to switch modes. The engine should now stay on all cylinders, so the subtle shudder, drone or hesitation that came with each change should be gone. If your dash shows instant fuel economy, expect the light-cruise numbers to read a little lower than before, since that is exactly where cylinder deactivation saved fuel.

Practical notes

The module uses the OBD-II port, so it has to come out whenever a technician or an inspection station needs the port. Plugging it back in restores the all-cylinder mode. Route it so the driver cannot kick it loose.

Module, tune or delete kit

A mechanical AFM delete swaps the deactivating lifters (and often the camshaft and lifter oil manifold) for non-AFM parts and requires a tune afterwards. A tune alone can switch AFM off in software. This module works through the OBD-II port instead, so the engine hardware and its calibration stay stock. That makes it the easiest option to reverse, and the right one only when the engine is mechanically healthy.

How to confirm your engine code

• Your model year, model and engine match a row in the table (2007–2018 GMC Sierra 1500).
• Look up the engine RPO code. Older GM vehicles print it on the Service Parts Identification sticker, often in the glovebox; 2018 and newer GM models carry it in a QR code on the driver-side B-pillar label. You can also read the 8th digit of the VIN, which is the engine code.
• No check-engine light is on, and oil level and pressure are normal.
• If the vehicle has an engine swap, an aftermarket tune or a replacement engine computer, contact support first.
• Questions: support@automotivebypass.com with your VIN.

Ordering details

Standard shipping inside the lower 48 states costs nothing; allow 1–2 business days of handling plus 3–4 in transit. Returns need approval first and must be requested within 45 days. Approved returns are subject to a 20% restocking fee, with return shipping paid by the customer. A 3-year limited warranty applies. Email support@automotivebypass.com (Mon–Fri, 9–5 PST) with your VIN if you want a fitment check.