Spark Plugs

Replace all six spark plugs on the 2017 Honda Ridgeline 3.5L V6 J35 engine, including ignition coil removal and installation.

Warnings

Tools required

Parts

• Spark plugs (NGK ILZKR7B11 or equivalent iridium) × 6 — NGK ILZKR7B11 or Honda 9807B-5617W

Preparation

1. Park vehicle on level ground and engage parking brake
2. Allow engine to cool completely (minimum 2 hours after operation)
3. Disconnect negative battery terminal to prevent accidental starter engagement
4. Verify replacement spark plugs are correct specification (NGK ILZKR7B11 or equivalent)

Procedure

1. 1

   Remove engine cover
   Grasp the engine cover firmly and pull upward to disengage the retention clips. The cover is held by push-in clips only and does not use fasteners. Set aside in a clean area.
2. 2

   Access rear bank spark plugs (cylinders 1, 3, 5)
   The rear bank (firewall side) plugs are accessed from above but are tight. Locate the three ignition coils on the rear cylinder bank. Depending on access, you may need to move wiring harnesses or hoses aside; verify whether any upper intake components require removal for rear bank access on this vehicle. Note: The rear bank (firewall side) plugs are located near the firewall. Access is restricted on this transverse-mounted engine — removal of the upper intake manifold cover and possibly the upper intake plenum and associated hoses/harness may be required to reach the rear bank coils and plugs. Verify access requirements against the service manual before proceeding.
3. 3

   Remove rear bank ignition coils
   Disconnect the electrical connector from each ignition coil by pressing the release tab and pulling straight up. Remove the single 10mm bolt securing each coil. Pull each coil straight up with a gentle twisting motion to release it from the spark plug well. Keep coils in order if reusing.
   Torque spec

   Ignition Coil Bolt8 Nm (6 lb-ft)
4. 4

   Clean rear spark plug wells
   Use compressed air or a shop vacuum to remove any debris from around the spark plug wells before removal. This prevents contamination from entering the cylinders.
5. 5

   Remove rear bank spark plugs
   Using the spark plug socket and extension, remove the three rear bank spark plugs (cylinders 1, 3, 5). Turn counterclockwise to remove. Inspect each plug for fouling, abnormal wear, or oil contamination which may indicate other engine issues.
6. 6

   Gap and prepare rear bank spark plugs
   Check the gap on each new spark plug using a gap gauge. Factory gap is approximately 0.040 inches (1.0-1.1mm). These iridium plugs come pre-gapped; only verify the gap and do not attempt to adjust it, as bending the fine electrode will damage the plug. Do NOT apply anti-seize compound to these plugs. Honda specifies installation of the factory iridium plugs dry; their plated threads are designed for installation without anti-seize, and using it can cause over-torquing and aluminum thread damage. Note: Do NOT apply anti-seize compound to these spark plug threads. The OE plugs have a plated anti-corrosion finish, and anti-seize changes the effective torque and can lead to over-tightening and stripped threads in the aluminum head. Install plugs clean and dry. Note: Factory gap is approximately 0.044 inches (1.1mm). These iridium plugs come pre-gapped from the factory — verify the gap only, and do NOT attempt to adjust it, as bending the fine iridium electrode can damage the plug.
7. 7

   Install rear bank spark plugs
   Thread each spark plug by hand into the cylinder head to avoid cross-threading. Once hand-tight, use the torque wrench to tighten to specification. Install all three rear bank plugs.
   Torque spec

   Spark Plug23 Nm (17 lb-ft)
8. 8

   Reinstall rear bank ignition coils
   Apply a small amount of dielectric grease to the inside of each coil boot if desired. Push each coil firmly into the spark plug well until fully seated. Install the 10mm retaining bolt and torque to specification. Reconnect the electrical connector to each coil until it clicks.
   Torque spec

   Ignition Coil Bolt8 Nm (6 lb-ft)
9. 9

   Access front bank spark plugs (cylinders 2, 4, 6)
   The front bank (radiator side) plugs are accessible from above. Locate the three ignition coils on the front cylinder bank. No additional components require removal for front bank access.
10. 10

    Remove front bank ignition coils
    Disconnect the electrical connector from each ignition coil by pressing the release tab and pulling straight up. Remove the single 10mm bolt securing each coil. Pull each coil straight up with a gentle twisting motion to release it from the spark plug well.
    Torque spec

    Ignition Coil Bolt8 Nm (6 lb-ft)
11. 11

    Clean front spark plug wells
    Use compressed air or a shop vacuum to remove any debris from around the spark plug wells before removal. Ensure no foreign material can fall into the cylinders.
12. 12

    Remove and install front bank spark plugs
    Remove the three front bank spark plugs (cylinders 2, 4, 6) using the spark plug socket. Verify the gap on each new plug, then install by hand (without anti-seize) before torquing to specification. Note: Remove the three front bank spark plugs (cylinders 2, 4, 6) using the spark plug socket. Verify the gap on each new plug, install by hand (clean and dry, no anti-seize) to avoid cross-threading, then torque to specification.
    Torque spec

    Spark Plug23 Nm (17 lb-ft)
13. 13

    Reinstall front bank ignition coils
    Apply dielectric grease to coil boots if desired. Push each coil firmly into place, install and torque the 10mm retaining bolt to specification, then reconnect each electrical connector.
    Torque spec

    Ignition Coil Bolt8 Nm (6 lb-ft)
14. 14

    Reinstall engine cover and reconnect battery
    Align the engine cover with the retention clips and press down firmly until all clips engage. Reconnect the negative battery terminal.

Reassembly

1. Ensure all ignition coil electrical connectors are fully seated and locked
2. Verify engine cover is securely clipped in place on all retention points
3. Double-check that all tools and parts have been removed from engine bay

Verification

• Start the engine and listen for smooth idle with no misfires or rough running
• Check for any diagnostic trouble codes using an OBD-II scanner
• Verify no ignition coil connectors were left disconnected
• Confirm there are no unusual noises or vibrations during idle and light acceleration

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

Chasing one of these codes and not sure which part is guilty? Ask a master mechanic about YOUR car →