CVT Transmission Assembly for 2016-2021 Honda Civic

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

• Check your VIN: Confirm that the 6th digit is a '1' or '3' (designating the 1.5L Turbo engine).
• Verify your Engine: Confirm you have the 1.5L Turbocharged engine (engine code L15B7).
• Locate the Transmission Tag: Confirm that the printed model code is BCGA or matches one of the verified IDs.
• Confirm Drivetrain: Ensure your vehicle is Front-Wheel Drive (FWD).

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

Special tools this job needs:

• Engine support bar/hoist
• Subframe jack/transmission jack
• Torque wrench
• Professional OBD2 scan tool capable of performing Honda CVT calibration
• Fluid pump or long-funnel system

Budget for these consumables at install:

• Genuine Honda HCF-2 Continuously Variable Transmission Fluid (5 to 8 quarts)
• Internal Pan Strainer (Honda Part Number 25420-5LJ-003)
• External Cartridge Filter (Honda Part Number 25450-P4V-013)
• Transmission oil pan gasket (Honda Part Number 21814-RJ2-003)
• Left and right CV axle seals
• Torque converter hub seal (input shaft seal)
• New drain plug crush washer (18mm) and check bolt crush washer (10mm)
• Professional transmission cooler line flush

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

What’s involved: Start Clutch Feedback Learning / Calibration / Adaptive Relearn

Whenever the transmission assembly is replaced, the PCM/TCM must relearn the feedback signal for the start clutch pressure control. A professional-grade scan tool with Honda-specific software (such as the Honda HDS) is required to perform the relearn procedure correctly.

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

• Torque Converter Seating: Must ensure the torque converter is fully seated onto the transmission input shaft and pump gears before bolting the transmission to the engine. If it is not fully seated, tightening the bellhousing bolts will pinch and crack the internal oil pump gear, instantly destroying the replacement transmission.
• The 'Hidden' Second Filter: Many general mechanics and DIYers do not realize this transmission has two filters. They change the pan filter but reuse the clogged external cartridge filter behind the warmer assembly, causing overheating and failure.
• Fluid Level Check Procedure: This transmission has no dipstick. Fluid level must be checked via a 17mm check bolt on the side of the case with the vehicle perfectly level and fluid temp between 95-113°F.
• Axle Seal Protection: When reinstalling the CV axles, use extreme caution not to nick or tear the rubber axle seals.
• Alignment Dowel Pins: Ensure the engine-to-transmission alignment dowel pins are present in the engine block to prevent severe vibration and damage to the torque converter.

Easy to get right once you know them:

• Using the Wrong Fluid: Filling the transmission with standard automatic transmission fluid (ATF) or generic multi-vehicle CVT fluid instead of genuine Honda HCF-2 fluid.
• Ordering for a 2.0L Engine: Assuming all 2016–2021 Civic automatic transmissions are identical. The 2.0L naturally aspirated engine uses a completely different CVT model (MCKA) with a different bellhousing bolt pattern.
• Skipping the Cooler Line Flush: Reintroducing metal debris from the failed unit into the replacement unit by failing to flush the cooler lines.
• Neglecting the Start Clutch Calibration: Skipping the TCM/PCM calibration after installation, leading to harsh shifting, shuddering, or slipping.

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: