2016 Dodge Challenger Spark Plug Replacement Guide — Step-by-Step

If you own a 2016 Dodge Challenger with the 3.6L Pentastar V6, you already know this engine is a sweetheart — smooth, reliable, and plenty torquey for everyday driving and the occasional highway romp. What most owners don't know until they go to do a tune-up is that the rear three spark plugs are a legitimate workout to access. I've done this job twice now, and I want to save you the frustration I had the first time I went in blind.

This guide covers the full plug swap on the 3.6L Pentastar — front bank, rear bank, the right plugs, and the right torque spec. Budget about 1.5–2 hours your first time.

Why Spark Plugs Matter on the Pentastar

The 3.6L Pentastar is used across a huge range of Chrysler/Dodge vehicles, which means there's a lot of collective experience with it. At 30,000–60,000 miles, worn plugs cause rough idle, slightly reduced fuel economy, and occasional cold-start misfires. The OEM plugs are copper-tipped and degrade faster than iridium replacements. Swapping to NGK Iridium IX plugs gets you better ignitability and a 60,000-mile service interval.

What You'll Need

• Plugs: NGK Iridium IX — Part #5787 (IZFR6K-11S) × 6
• 3/8" drive ratchet + extension (3" and 6")
• 5/8" spark plug socket (with rubber insert)
• Universal joint / flex socket (essential for rear bank)
• Torque wrench (ft-lb)
• Dielectric grease (small amount for boot tips)
• Compressed air or vacuum (to clear plug wells before removal)
• Anti-seize — NOT recommended for iridium plugs per NGK spec

Front Bank (Cylinders 1, 3, 5) — The Easy Side

1. Let the engine cool completely — at least 2 hours after last run. Hot aluminum threads strip easily.
2. Remove the engine cover if equipped — usually two push clips at the rear.
3. Locate cylinders 1, 3, 5 — these are the front bank plugs, accessible from the top of the engine.
4. Blow out each plug well with compressed air before removing the coil. Dirt and grit sitting in the well goes straight into the cylinder if you skip this.
5. Disconnect the coil-on-plug (COP) connector — press the tab and pull straight back.
6. Remove the COP bolt (8mm) and pull the coil straight up. Set it aside — don't tug by the connector wire.
7. Thread in your plug socket and extension. Break the plug loose counter-clockwise, then spin out by hand.
8. Inspect the old plug — electrode wear, deposits, oil fouling. Normal wear shows a slightly worn electrode. Oil on the threads or a black sooty electrode means investigate further before just putting new plugs in.
9. Install the new NGK Iridium IX — thread in by hand until snug. Torque to 13 ft-lbs (18 Nm). Do not over-torque — aluminum heads are unforgiving.
10. Apply a tiny smear of dielectric grease to the inside of the coil boot tip (not the plug terminal itself).
11. Reinstall COP — press down firmly until you feel it seat, then reinstall the 8mm bolt. Torque to 89 in-lbs (10 Nm).

Rear Bank (Cylinders 2, 4, 6) — The Real Job

This is where first-timers get surprised. The rear three cylinders on the Pentastar face the firewall, which means you have very little straight-line clearance. You need a universal joint in your extension stack.

12. Work from above — you can reach all three from the top of the engine, but patience is required.
13. Disconnect the COP connector — same press-tab method, but you'll be doing it partly by feel.
14. Remove the COP bolt (8mm) and extract the coil. On cylinder 2 especially, wiggling the coil at an angle helps clear the firewall.
15. Use the universal joint on your extension before the plug socket. The u-joint allows you to angle the socket into the plug well even with the firewall right there.
16. Blow out the well, break the plug loose, spin out by hand.
17. Thread in the new NGK Iridium IX — by hand first. This is where the u-joint bites you if you rush: you need to feel that the plug is threading straight. If there's resistance, back it out and start again. Cross-threading an aluminum head on the rear bank is an expensive mistake.
18. Torque to 13 ft-lbs (18 Nm) using the u-joint extension. Check that your torque wrench is reading true through the flex — some cheap u-joints introduce error. Use a quality socket and short u-joint.
19. Reinstall COP, snap connector, reinstall bolt at 89 in-lbs.

Restart and Verify

Once all six plugs and coils are reinstalled, reconnect battery if you disconnected it. Start the engine — it should fire right up. Let it idle for 3–5 minutes and listen for any misfires. If you get a P030X misfire code, the coil on that cylinder may not be fully seated — check the boot and bolt.

Cost Comparison: DIY vs. Shop

	DIY	Dealer/Shop
6 NGK Iridium IX plugs	$35–$55	Included
Labor	$0	$180–$280
Total	$35–$55	$250–$350+

Common Mistakes to Avoid

• Skipping the rear bank — don't just do the easy front three. You'll be back in here in 6 months for the rears.
• Using anti-seize on iridium plugs — NGK explicitly says no. Their iridium plugs have a nickel-plated shell that provides adequate lubrication.
• Not using a torque wrench — 13 ft-lbs is modest. It's easy to blow past it by feel.
• Rushing the rear bank hand-threading — take your time. A cross-threaded plug in an aluminum head is a much bigger job than doing this right.

For more on Dodge and Chrysler maintenance procedures, browse the OwnerDrop blog — there are dedicated guides for Charger, Durango, and Jeep Pentastar variants.

Get the full guide + every torque spec in the OwnerDrop library — OwnerDrop /pricing.