Valve Cover Gaskets - Both

This procedure covers the replacement of the valve cover gasket and spark plug tube seals on the 2016-2021 Honda Civic 1.5L turbocharged engine to eliminate oil leaks from the cylinder head cover.

Warnings

Tools required

Parts

• Valve cover gasket × 1 — Use OEM Honda part 12341-5AA-A01 or equivalent
• Spark plug tube seals × 4 — Use OEM Honda part 12342-5AA-A01 or equivalent
• PCV valve grommet (if deteriorated) × 1 — Use OEM specification

Fluids

• Honda Genuine 0W-20 Engine Oil — 0.5 qt

Preparation

1. Ensure engine is completely cool to the touch
2. Disconnect negative battery terminal and wait 3 minutes
3. Remove engine cover by pulling upward on the front edge to release clips
4. Verify you have the correct replacement gasket and spark plug tube seals for the L15B7 turbocharged engine
5. Position vehicle on level ground with parking brake engaged

Procedure

1. 1

   Remove ignition coils
   Disconnect the electrical connectors from all four ignition coils by pressing the release tab and pulling straight up. Remove the 10mm bolts securing each ignition coil. Carefully pull each coil straight out of the spark plug tube. Mark or photograph coil positions for correct reinstallation.
   Torque spec

   Ignition Coil Bolts8 Nm (6 lb-ft)
2. 2

   Remove spark plugs
   Using a spark plug socket with extension, remove all four spark plugs. Inspect plugs for condition and gap. Keep plugs organized by cylinder position for inspection purposes. This provides access to the spark plug tube seals and prevents debris from entering cylinders during gasket replacement.
   ⚠Ensure no debris falls into spark plug holes. Cover openings with clean shop towels if work is interrupted.
   Torque spec

   Spark Plugs - Aluminum Head20 Nm (15 lb-ft)
3. 3

   Disconnect PCV hose and breather tube
   Disconnect the PCV hose from the rear of the valve cover by squeezing the quick-disconnect fitting and pulling away. Disconnect the breather tube from the left side of the valve cover in the same manner. On some models, you may need to release a wiring harness clip attached to the valve cover.
4. 4

   Remove wiring harness brackets
   Locate and remove any wiring harness brackets or clips mounted to the valve cover bolts. These typically use the same 10mm bolts that secure the valve cover. Carefully move wiring harnesses aside to provide clear access to all valve cover bolts.
5. 5

   Remove valve cover bolts
   Remove all valve cover bolts in a cross-pattern sequence starting from the outside and working inward. There are typically 11 bolts securing the valve cover on this engine. Keep bolts organized as some may be different lengths. Note the location of any brackets or grounds attached to specific bolts.
   Torque spec

   Cover Bolts15 Nm (11 lb-ft)
6. 6

   Remove valve cover
   Gently lift the valve cover straight up. If stuck, use a plastic pry tool at designated pry points (never between sealing surfaces). Rock the cover gently side to side while lifting. The cover may be sealed with old gasket material. Do not pry between mating surfaces as this will damage the sealing surface on the cylinder head.
   ⚠Never use metal tools to pry between the valve cover and cylinder head as this will cause permanent damage to sealing surfaces.
7. 7

   Remove old gasket and spark plug tube seals
   Remove the old valve cover gasket from the groove in the valve cover. Using needle nose pliers, carefully extract the four old spark plug tube seals from the valve cover. These are press-fit rubber seals located around each spark plug tube opening. Inspect the PCV valve grommet and replace if cracked or hardened.
8. 8

   Clean all sealing surfaces
   Thoroughly clean the valve cover gasket groove and mating surface using brake cleaner and a lint-free cloth. Clean the cylinder head sealing surface, being extremely careful not to let debris fall into the engine. Use compressed air to blow away any remaining particles. Ensure spark plug tube areas on both the head and cover are completely clean and dry. All surfaces must be free of oil, old gasket material, and debris.
   ⚠Cover open camshaft area with clean towels to prevent any debris from entering the engine during cleaning.
9. 9

   Install new spark plug tube seals
   Lightly lubricate the new spark plug tube seals with clean engine oil. Press each seal firmly into its bore in the valve cover by hand until it seats completely flush. Ensure seals are properly oriented and seated evenly around the entire circumference. The seals should sit below the valve cover surface.
   ℹ️These seals are press-fit only and require no torque. Ensure complete seating to prevent oil leaks into spark plug tubes.
10. 10

    Install new valve cover gasket
    Place the new valve cover gasket into the groove in the valve cover (not on the cylinder head). Ensure the gasket is fully seated in the groove around the entire perimeter and at all bolt holes. The gasket should fit snugly without gaps or overlapping. Verify gasket orientation matches the old gasket configuration.
11. 11

    Install valve cover
    Carefully position the valve cover onto the cylinder head, ensuring proper alignment with all bolt holes. Lower the cover straight down to avoid displacing the gasket. Do not slide or shift the cover once it contacts the head. Verify the gasket remains properly seated in its groove.
12. 12

    Torque valve cover bolts in sequence
    Install all valve cover bolts finger-tight, ensuring any wiring harness brackets and ground straps are reinstalled in their original positions. Using a torque wrench, tighten bolts to specification in a cross-pattern sequence from the center outward. Make multiple passes, first to 5 Nm, then to final torque specification. This ensures even gasket compression and proper sealing.
    ⚠The valve cover is plastic. Overtightening will crack the cover or cause gasket distortion and leaks. Use precise torque values.
    Torque spec

    Cover Bolts15 Nm (11 lb-ft)
13. 13

    Install spark plugs
    Apply a small amount of anti-seize compound to the threads of each spark plug (avoid getting any on the electrode). Install spark plugs by hand into their respective cylinders, ensuring they thread smoothly without cross-threading. Torque to specification using a torque wrench. Verify the correct gap if reusing old plugs.
    ⚠Cross-threading spark plugs in the aluminum head will cause extensive and expensive damage. Always start by hand and ensure smooth threading.
    Torque spec

    Spark Plugs - Aluminum Head20 Nm (15 lb-ft)
14. 14

    Install ignition coils
    Apply a small amount of dielectric grease to the inside of each ignition coil boot. Press each ignition coil firmly into its spark plug tube until it seats completely on the spark plug. Install and torque the ignition coil bolts to specification. Reconnect all ignition coil electrical connectors, ensuring they click into place securely.
    Torque spec

    Ignition Coil Bolts8 Nm (6 lb-ft)
15. 15

    Reconnect hoses and final assembly
    Reconnect the PCV hose and breather tube to the valve cover, ensuring quick-disconnect fittings click into place securely. Reattach any wiring harness clips to the valve cover. Reconnect the negative battery terminal. Reinstall the engine cover by aligning the clips and pressing down firmly until it clicks into place.

Reassembly

1. Double-check that all electrical connectors are fully seated and latched
2. Verify PCV and breather hoses are securely connected with no vacuum leaks
3. Ensure no tools or rags were left in the engine compartment
4. Confirm all valve cover bolts are present and properly torqued

Verification

• Start the engine and listen for any unusual ticking or vacuum leak sounds that would indicate improper coil seating or hose connection
• Allow engine to reach operating temperature and visually inspect the valve cover perimeter for any oil seepage
• Check for oil in spark plug tubes after several heat cycles (remove engine cover and ignition coils to inspect)
• Verify no check engine lights or misfire codes are present using an OBD-II scanner
• After 50-100 miles of driving, re-inspect valve cover area for any signs of oil leakage and verify gasket is sealing properly

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