Transmission Pan Gasket

This procedure covers removal and replacement of the transmission pan gasket on the 2016-2021 Honda Civic 1.5L Turbo with automatic transmission, including fluid drainage and refill.

Warnings

Tools required

Parts

• Transmission pan gasket × 1 — Use OEM Honda gasket
• Transmission drain plug crush washer × 1 — 94109-20000 or equivalent

Fluids

• Honda DW-1 ATF — 4 qt

Preparation

1. Park vehicle on level surface and apply parking brake
2. If recently driven, allow transmission to cool for at least 30 minutes
3. Raise front of vehicle and support securely on jack stands
4. Remove plastic engine/transmission splash shield if equipped (multiple plastic clips and bolts)
5. Place drain pan underneath transmission pan area

Procedure

1. 1

   Drain transmission fluid
   Locate the transmission drain plug on the bottom of the transmission pan. Using the appropriate socket, slowly loosen and remove the drain plug. Allow fluid to drain completely into the drain pan (approximately 3-4 quarts will drain). Inspect the drain plug and washer for damage.
   Torque spec

   Transmission Drain Plug30 Nm (22 lb-ft)
2. 2

   Remove transmission pan bolts
   Once fluid has fully drained, locate all transmission pan bolts around the perimeter of the pan (typically 14-16 bolts). Using a criss-cross pattern, loosen each bolt gradually in multiple passes to prevent warping the pan. Remove all bolts and set aside, keeping track of any different length bolts and their positions.
   Torque spec

   Pan Bolts15 Nm (11 lb-ft)
3. 3

   Remove transmission pan
   Carefully lower the transmission pan. Some residual fluid will remain in the pan, so tilt slowly to avoid spilling. Remove the pan completely and set aside. Be prepared for additional fluid to drain from the transmission body.
   ⚠Pan will contain 1-2 quarts of residual fluid. Lower carefully to avoid spills.
4. 4

   Inspect internal components
   With the pan removed, visually inspect the transmission filter (if visible), magnet in the pan, and internal components for excessive debris or metal particles. The magnet will have some fine metallic residue, which is normal. Excessive chunks or material indicate potential transmission wear requiring further diagnosis.
   ℹ️Some metal residue on the magnet is normal. Excessive debris may indicate transmission wear.
5. 5

   Clean gasket surfaces
   Remove the old gasket from both the transmission pan and the transmission body mating surface. Use a plastic scraper or gasket scraper to carefully remove all old gasket material without gouging the metal surfaces. Clean both surfaces thoroughly with brake cleaner and wipe dry with clean shop rags. Surfaces must be completely clean and dry for proper gasket sealing.
   ⚠Do not gouge or scratch the aluminum transmission housing or pan mating surfaces. Damage will cause leaks.
6. 6

   Clean transmission pan and magnet
   Thoroughly clean the inside of the transmission pan, removing all fluid residue and debris. Clean the magnetic drain plug thoroughly to remove all accumulated metal particles. Inspect the pan for cracks, damage, or warping. Dry completely before reinstallation.
7. 7

   Install new gasket
   Position the new transmission pan gasket onto the clean transmission pan. Ensure the gasket is properly aligned with all bolt holes and fits evenly around the pan perimeter. Some gaskets are adhesive-backed for easier installation. Do not use additional sealant unless specified by Honda.
   ℹ️Do not use RTV or additional sealant with the gasket unless specifically required by the service manual.
8. 8

   Install transmission pan
   Carefully raise the transmission pan with new gasket into position against the transmission body. Start all pan bolts by hand, ensuring proper thread engagement. Do not force any bolts. Verify the gasket remains properly positioned.
9. 9

   Torque transmission pan bolts
   Using a criss-cross pattern starting from the center and working outward, tighten the transmission pan bolts gradually in multiple passes. First pass: snug by hand. Second pass: 6 Nm (4 lb-ft). Final pass: torque to specification. This ensures even gasket compression and prevents warping.
   ⚠Must use criss-cross tightening pattern to prevent pan warping and ensure proper gasket seal.
   Torque spec

   Pan Bolts15 Nm (11 lb-ft)
10. 10

    Install drain plug with new washer
    Install the new crush washer onto the drain plug. Thread the drain plug into the transmission pan by hand to ensure proper engagement. Torque the drain plug to specification using a torque wrench.
    Torque spec

    Transmission Drain Plug30 Nm (22 lb-ft)
11. 11

    Refill transmission fluid
    Locate the transmission fill plug on the side of the transmission case. Remove the fill plug. Using a funnel with long hose inserted into the fill hole, add approximately 3.5-4.0 quarts of Honda DW-1 ATF (the amount drained from the pan). Install the fill plug temporarily.
    ℹ️Initial fill amount equals approximately what was drained. Final level will be verified with engine running.
12. 12

    Reinstall splash shield and lower vehicle
    Reinstall the engine/transmission splash shield with all clips and fasteners. Lower the vehicle from jack stands to the ground.

Reassembly

1. Verify all tools and materials are removed from under vehicle
2. Ensure drain pan is positioned to catch any potential leaks during first start
3. Double-check all fasteners are properly torqued before starting engine

Verification

• Start the engine and allow it to reach normal operating temperature (approximately 5-10 minutes)
• With engine running and transmission in Park on level ground, remove the fill plug and check fluid level - fluid should trickle slowly from the fill hole when at proper level and temperature
• Add fluid as needed through fill hole until proper level is achieved, then reinstall fill plug
• Inspect underneath vehicle for any fluid leaks around the transmission pan and drain plug
• Test drive vehicle through all gears to verify proper transmission operation
• Recheck fluid level after test drive and top off if necessary
• Inspect again for leaks after test drive - any seepage indicates improper installation

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