Buick Terraza 2006-2008 3.9L V6 & Regal GS 2018 3.6L V6 AFM/DFM Disabler

Fits the 2006–2008 Buick Terraza and 2018 Buick Regal GS. The module connects at the OBD-II port and keeps GM's cylinder deactivation from switching on, which means steady all-cylinder operation instead of repeated changes between full and partial mode. Installation is plugging it in. Nothing is spliced, flashed or removed from the engine, and the factory system resumes as soon as the module is unplugged.

Fitment by year and engine

The fitment table for this part (all rows marked 100% fitment match):

• 2006–2008 Buick Terraza: 3.9L V6
• 2018 Buick Regal GS: 3.6L V6

Confirm that your exact engine is the one in the table and that it uses cylinder deactivation. The RPO label and the VIN engine digit are the reliable ways to check, and support can confirm from a VIN.

How Active Fuel Management operates

GM's cylinder deactivation saves fuel by running the engine on fewer cylinders during light-load cruising. The switch is controlled by the engine computer. The module talks to the vehicle through the OBD-II port and keeps that reduced-cylinder mode from being selected, so all cylinders stay active.

Other ways owners disable AFM

Owners who want AFM gone for good sometimes go the mechanical route: non-AFM lifters, a matching camshaft and a retune. That is a large job and it is permanent. A tuner can also disable AFM in the engine computer. The plug-in module sits at the other end of the scale: no parts replaced, no software rewritten, and back to factory with one pull. It is meant for engines that run well and simply should not switch modes.

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.

Before installing

Scan for stored codes before you plug it in. Misfire codes on the deactivation cylinders, an AFM solenoid circuit code, or a lifter noise are signs of an existing problem that should be repaired first. The module is meant for a healthy engine where you simply do not want cylinder deactivation.

Oil and maintenance

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.

After installation

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.

How to confirm your engine code

• Your model year, model and engine match a row in the table (2006–2008 Buick Terraza and 2018 Buick Regal GS).
• 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.
• The engine runs cleanly with no stored misfire or AFM codes.
• 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.

Shipping and support

We ship free within the contiguous United States (1–2 business days to dispatch, roughly 3–4 business days in transit). If it turns out to be the wrong part, request a return authorization within 45 days; returns carry a 20% restocking fee and return postage is on the buyer. Coverage is a 3-year limited warranty. Questions go to support@automotivebypass.com, weekdays 9 a.m. to 5 p.m. PST.