2016 Honda Odyssey Spark Plug Replacement — Complete DIY Guide

The 2016 Honda Odyssey runs Honda's 3.5L J35Y2 V6 — six cylinders, two banks of three, and the rear bank is the reason this job has a reputation for being "hard." It's not hard. It just requires removing the intake plenum — a 45-minute sub-task that gives you full access to everything. Once you've done it, the whole job is completely manageable for any home mechanic. You'll save $300–$400 over Honda dealer pricing.

What You'll Need

• Spark plugs: NGK Iridium IZF R6K11 (Honda OEM: Denso SK20HR11 or NGK ILZKR7B11)
  • Pack of 6 — confirm iridium spec, do NOT use copper on this engine
  • All 6 plugs should be replaced together regardless of condition
• 5/8" spark plug socket (with rubber insert)
• 3/8" drive ratchet
• 3" and 6" extensions
• 10mm socket (valve cover bolts and coil mounting bolts)
• 8mm socket (intake plenum bolts — many are 8mm on the J35Y2)
• Torque wrench (accurate at low values — 13 ft-lbs)
• Dielectric grease
• Compressed air
• Ratcheting wrench or flex-head ratchet (helps in tight spots)
• Intake plenum gasket set (Honda OEM or Fel-Pro replacement — the gasket is typically reusable if undamaged but replace if it's been compressed many times)
• Shop rags and brake cleaner

Estimated time: 2.5–3.5 hours (including intake plenum removal and reinstallation) Estimated cost: $50–$80 in parts (vs. $350–$450 at a Honda dealer)

Why the Rear Bank Requires Intake Plenum Removal

The J35Y2 V6 in the 2016 Odyssey is a transversely mounted (sideways) V6. The front bank (cylinders 1, 3, 5) faces toward you in the engine bay and is directly accessible. The rear bank (cylinders 2, 4, 6) faces the firewall. Without removing the upper intake manifold (plenum), you physically cannot reach the rear bank coils or plug wells with standard tools.

Some guides suggest you can access the rear bank by removing only the intake tube and working around the plenum. Technically possible on some vehicles, but on the Odyssey the clearances are too tight for any sensible approach. Remove the plenum. It takes 45 minutes and gives you clean, safe access. You'll be glad you did it right.

Step-by-Step Instructions

Step 1: Front Bank First (Easy)

1. Let the engine cool completely — 2+ hours after driving.
2. Remove the engine cover — Two or three bolts or pop-off grommets. Set aside.
3. Blow compressed air into each front plug well before removing anything.
4. Front bank coils (cylinders 1, 3, 5) — Disconnect the coil connectors (press tab, pull straight up). Remove the 10mm mounting bolt per coil. Pull coil straight up. May need to twist to break the boot free from the plug.
5. Remove front bank plugs — 5/8" socket with 3" extension. Counterclockwise. Pull each plug. Inspect.
6. Thread in new front bank plugs by hand — Confirm thread engagement by hand before using a wrench. Torque to 13 ft-lbs (18 Nm).
7. Apply dielectric grease inside coil boots — Thin ring inside the rubber tip.
8. Reinstall front coils and connectors.

Step 2: Intake Plenum Removal (Rear Bank Access)

9. Disconnect the negative battery terminal — 10mm bolt. The intake plenum work involves wiring harness and electrical connectors.
10. Disconnect the air intake tube from the throttle body (spring clamp at the throttle body, 8mm or hose clamp at the air box end). Remove the intake tube from the engine bay.
11. Disconnect the throttle body electrical connector and any vacuum lines connected to the throttle body.
12. Remove the brake master cylinder vacuum hose from the intake plenum if it's routed across the top (varies by trim).
13. Identify and label all vacuum and PCV hoses connecting to the plenum — take a phone photo before disconnecting. There are typically 4–6 connections.
14. Disconnect all vacuum/PCV hoses from the plenum.
15. Remove the intake plenum bolts — Typically 8–10 bolts (8mm or 10mm), arranged around the perimeter of the plenum flange. Remove all bolts and set them aside in order.
16. Lift the plenum off the lower intake manifold — It will be stubborn due to the gasket. A gentle twist while pulling usually breaks it free. Don't pry with metal tools against the sealing surfaces.
17. Set the plenum aside safely — Note the gasket condition. Reuse if intact; replace if cracked or deformed.

Step 3: Rear Bank Spark Plugs

18. Rear bank coils now fully visible — Cylinders 2, 4, 6. Same procedure as front: disconnect connector, remove 10mm bolt, pull coil up.
19. Blow compressed air into rear plug wells — Now that the plenum is off, this is actually easy to do properly.
20. Remove rear bank plugs — 5/8" socket with 6" extension. Counterclockwise.
21. Inspect all rear plugs — Compare to front bank plugs. Rear bank plugs on transverse V6 engines often look slightly different from front bank due to combustion characteristics of the bank position.
22. Install new rear plugs by hand, torque to 13 ft-lbs (18 Nm).
23. Apply dielectric grease and reinstall rear coils and connectors.

Step 4: Reassembly

24. Clean the lower intake manifold sealing surface — Remove any old gasket material with a plastic scraper and brake cleaner.
25. Install plenum gasket — New gasket (recommended) or carefully reinstall the original if it's in perfect condition.
26. Lower the plenum onto the manifold — Align all bolt holes. Start all bolts by hand before torquing any.
27. Torque plenum bolts — Working from center outward in a crossing pattern, torque to 16 ft-lbs (22 Nm).
28. Reconnect all vacuum and PCV hoses — Use your photo as reference. Every hose must be reconnected or you'll have a vacuum leak at startup.
29. Reconnect throttle body connector and reinstall intake tube.
30. Reconnect battery terminal.
31. Reinstall engine cover.
32. Start engine — Should start and run smoothly. A rough idle for 10–15 minutes while the ECU relearns throttle position is normal after battery disconnect. If rough idle persists beyond 20 minutes, check vacuum hose connections.

Pro Tips / Common Mistakes

• Photograph the vacuum hoses before disconnecting — The J35Y2's plenum has multiple vacuum ports. One missed or reversed hose = rough idle or check engine light.
• Don't skip the rear bank — Owners who've done "partial" spark plug jobs on this engine (front bank only) often have misfires from the worn rear plugs within a few months. Do all six.
• 13 ft-lbs torque spec — Lower than most V8s and trucks. Torque wrench, every plug.
• Iridium plugs only — The J35Y2 coil-on-plug system is designed for iridium. Copper plugs will work but require 30,000-mile intervals. With iridium, Honda recommends 60,000–90,000 miles.

Cost Comparison: DIY vs. Shop

	DIY	Honda Dealer
6 NGK iridium plugs	$45–$65	Included
Intake gasket (if replacing)	$10–$20	Included
Labor	$0	$250–$350
Total	$55–$85	$350–$450

For more Honda Odyssey maintenance guides — transmission fluid, brake service, oil changes — browse all articles at /blog.

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