CVT Transmission Assembly for 2020-2025 Buick & Chevrolet • Encore GX, Trailblazer

A quick look at your own vehicle makes sure the right transmission shows up:

• Confirm the vehicle is Front-Wheel Drive (FWD) and not All-Wheel Drive (AWD).
• Confirm the vehicle has the 1.2L turbocharged 3-cylinder engine (RPO code LIH).
• Locate the QR code label on the driver's door B-pillar or the Service Parts Identification sticker in the glove box and verify RPO code MRG is present (and not M3F).

What the install really takes — plan and budget with confidence:

Special tools this job needs:

• Transmission jack
• Engine support bar
• Kent-Moore DT-52316 octagon socket tool (for external filter cap)
• Professional-grade scan tool with GM SPS2 subscription

Budget for these consumables at install:

• ACDelco GM Original Equipment HPCVT Automatic Transmission Fluid (GM Part #19355873 / ACDelco Part #10-4118 or GM Part #19418016)
• External Cartridge Filter (GM Part #24290959)
• Internal Sump Filter (GM Part #24292809 or #24288521)
• Oil Pan Gasket (GM Part #24273651)
• Torque Converter Seal (GM Part #24289734)
• Front axle seals (both sides)
• Approved transmission cooler flush solvent

What your vehicle’s computers will need after the swap:

What’s involved: Solenoid Characterization Reprogramming (MCVM - Mechanical Characterization and Virtual Matching) and Transmission Service Fast Learn

The VT40 transmission uses a unique 16-digit Transmission Unique Number (TUN) printed on a barcode label on the case. This TUN must be programmed into the vehicle's TCM using GM's Service Programming System (SPS2) software and a J2534 pass-through device (or GM MDI2 scan tool) to download specific flow characterization data from GM's cloud server. After programming, a Transmission Service Fast Learn (adaptive relearn) must be performed. Failure to program will result in a no-start condition, poor shifting, slipping, or trouble codes.

Pro tips for a smooth first start-up — hand them to whoever does the install:

• TUN Documentation: You must write down or take a photo of the 16-digit Transmission Unique Number (TUN) on the barcode label before installing. Once bolted in, the label is blocked and impossible to read.
• Torque Converter Seating: Ensure the torque converter is fully seated onto the transmission pump shaft before bolting the transmission to the engine. If not fully seated, tightening the bellhousing bolts will crack the front pump gear, instantly ruining the transmission.
• Filter Cap Tool (DT-52316): The external cartridge filter is under a high-pressure plastic cap on the side of the case. You must use the special Kent-Moore DT-52316 octagon socket tool to remove and torque it to 60 Nm (44 lb-ft) to avoid cracking the plastic cap.
• Fluid Level Check Procedure: The VT40 has no dipstick. Check fluid level through the overflow plug on the side of the case with fluid temperature strictly between 60°C and 80°C (140°F to 176°F), engine running, vehicle level, and A/C off.
• Cooler Contamination: The transmission fluid cooler and lines must be professionally flushed to remove any metal shavings or clutch material from the previously failed unit.
• Ground Straps: Ensure all chassis-to-transmission ground straps are clean and securely reconnected to prevent electronic behavior and shifting problems.

Easy to get right once you know them:

• Using the Wrong Fluid: Using standard Dexron VI or multi-vehicle ATF instead of GM HP CVTF (HPCVT) fluid. Standard ATF lacks the specific friction coefficients required, causing immediate belt/chain slippage and catastrophic internal failure.
• Skipping Solenoid Characterization (TUN Programming): Assuming a used transmission is plug-and-play. Skipping the TUN programming will cause the TCM to use incorrect solenoid flow rates, leading to harsh shifts, slipping, and DTC P2714.
• Cracking the Plastic Filter Cap: Attempting to remove or torque the external filter cap with standard channel locks, strap wrenches, or standard sockets instead of the specialized Kent-Moore tool.
• Incorrect Fluid Level Check: Checking the fluid level with the engine off, or at the wrong temperature, which leads to severe underfilling and immediate slippage.
• Ignoring the Cooler Flush: Skipping the cooler flush, which introduces contamination from the old failed unit into the replacement, voiding the warranty and causing a second failure.
• Forcing the Bellhousing: Using the bellhousing bolts to draw the engine and transmission together when they do not mate perfectly, which cracks the transmission's internal oil pump.

Not issues with the units on this page — the manufacturer documented these for every transmission of this family, wherever you buy one. Handy for your installer: