CVT Transmission Assembly for 2021 Honda Civic

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

• Verify that the 6th digit of your VIN is either 2 or 4.
• Verify that the engine block stamp or emissions label reads K20C2 (2.0L 4-cylinder).
• Locate the white barcode sticker on the side of the current transmission case and verify it displays the code JDJC.

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

Special tools this job needs:

• Engine support bar/brace/hoist
• Subframe jack/hoist/transmission jack
• CV axle puller
• Torque wrench
• Professional OBD2 scan tool capable of Honda-specific functions

Budget for these consumables at install:

• Genuine Honda CVT Fluid HCF-2 (Do NOT use standard ATF or multi-vehicle CVT fluids)
• Internal Strainer/Filter (Part # 25420-5LJ-003)
• Warmer/Cartridge Filter (Part # 25450-P4V-013)
• Oil pan gasket (Part # 21814-RJ2-003)
• Warmer filter O-rings (Part # 25565-5LJ-A01 and 25564-5LJ-A01)
• New drain plug crush washer (90471-PX4-000)
• Level check plug crush washer (94109-20000)
• Axle seals
• Torque converter seal
• Professional transmission cooler line flush

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

What’s involved: CVT Start Clutch Calibration / Pressure Control Calibration (Start Clutch Feedback Learning Procedure)

After installation, the transmission's adaptive learning values must be reset, and a start clutch pressure control calibration must be performed. While some sources mention a manual driving/shifting sequence, using a professional dealer-level scan tool (such as Honda i-HDS or a high-end bi-directional scanner) is highly recommended to ensure accuracy and prevent harsh shifting or shuddering.

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

• The Two-Filter Secret: This transmission has two filters (pan strainer and warmer filter). Both must be replaced during the swap.
• Torque Converter Seating: Ensure the torque converter is fully and correctly seated into the transmission's front pump before bolting to the engine. If not fully seated, tightening the bellhousing bolts will crack the internal oil pump or transmission case.
• Fluid Level Check Procedure: No traditional dipstick is present. The fluid level must be checked using the level check plug (overflow bolt) on the side of the case. The vehicle must be perfectly level, fluid temperature must be within 95°F to 113°F (35°C to 45°C), and the engine must be run through all gears before removing the check plug.
• Subframe Alignment: Dropping the front subframe is required. Mark the subframe alignment or use alignment pins when reinstalling to avoid steering wheel off-center issues.
• Use the New Torque Converter: Use the torque converter provided with the replacement transmission; do not reuse the old one.

Easy to get right once you know them:

• Ordering the wrong transmission for a 1.5L Turbo engine instead of the 2.0L naturally aspirated engine.
• Using aftermarket or universal CVT fluid instead of genuine Honda HCF-2 fluid.
• The 'Ramp' Leveling Mistake: Draining and filling the transmission while the car is on front ramps instead of being completely level on jack stands or a lift.
• Skipping the transmission cooler line flush, which recontaminates the replacement unit with debris from the failed unit.
• Forgetting or ignoring the electronic Start Clutch Calibration / TCM adaptive relearn procedure.

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: