CVT Transmission Assembly for 2018-2021 Subaru WRX

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

• Verify the 8th digit of the VIN to confirm the 2.0L Turbocharged FA20F/FA20DIT engine.
• Check the B-pillar manufacturer plate on the driver's side door frame to confirm the transmission code begins with TR690 (e.g., TR690GB6BA).
• Confirm the vehicle is equipped with Symmetrical All-Wheel Drive (AWD).

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

Special tools this job needs:

• Engine support bar/hoist
• Transmission jack
• Bi-directional OBD2 scan tool with Subaru-specific software
• Fluid transfer pump
• Torx T70 bit

Budget for these consumables at install:

• Subaru High-Torque CVT Fluid (HT-CVTF, Orange/Red, Part #K0421Y0700)
• Transmission pan gasket or RTV sealant
• Internal fluid strainer/filter
• Front torque converter seal (pump/input shaft seal)
• Front axle seals
• Professional-grade transmission cooler line flush solvent
• 75W-90 gear oil (for the separate front differential chamber)

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

What’s involved: TCM Adaptive Relearn (AT Learning Mode)

A TCM adaptive relearn is mandatory. The TCM stores learned values from the previous unit which must be cleared. The relearn process calibrates the TCM to the physical tolerances of the replacement unit's internal clutches and pulleys. Skipping this step results in harsh shifting, slipping, and potential damage.

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

• Torque Converter Seating: Must be fully seated (typically three distinct clicks/drops) before bolting the bellhousing. Failure to seat it fully will crush and destroy the internal oil pump upon installation.
• The Two Drain Plugs Trap: The engine oil drain plug and the CVT drain plug are close together. Do not accidentally drain the CVT fluid during an oil change, or vice versa.
• Critical Fluid Fill Temperature: The transmission has no dipstick. The fluid level must be checked via the check plug only when the fluid temperature is strictly within the target range (sources differ: 35-45°C vs 30-40°C). Checking outside this range causes incorrect fill levels.
• Front Differential Isolation: The front differential is integrated into the housing but uses a completely separate chamber lubricated by 75W-90 gear oil, NOT CVT fluid. Do not drain it by mistake or mix the fluids.
• Do Not Use a Flush Machine: High-pressure flush machines can force debris into the valve body. Perform a drain and fill on the transmission, and flush the external cooler lines separately while disconnected.

Easy to get right once you know them:

• Using Generic or Wrong CVT Fluid: Using standard green/blue Subaru CVTF-II/III or generic multi-vehicle fluid will cause rapid, catastrophic chain slippage and failure.
• Failing to Flush the Cooler Lines: Debris from the previous failed transmission will flow into the replacement unit's valve body and ruin it if lines are not flushed.
• Skipping the AT Learning Mode: Operating the replacement transmission on old adaptive values leads to immediate slipping, harsh engagement, and error codes.
• Misidentifying the Front Differential Chamber: Accidentally draining the front differential and filling the CVT chamber leaves the differential dry, destroying the front gears on the first drive.
• Believing in Lifetime Fluid: Failing to change the fluid on a used high-mileage unit poses a significant risk.

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: