Jeep 3.6 Spark Plugs — Pull the Intake, Torque to 13 ft-lbs

Passenger-side plugs on a 2012–2018 Wrangler 3.6 are a coil-and-socket job. Driver-side plugs sit under the upper intake. You pull the plenum, replace all six, torque the plugs to 13 ft-lbs (17.5 N·m / 156 in-lbs), the coils to 71 in-lbs (8 N·m), and the intake back on at 89 in-lbs (10 N·m). No anti-seize. No silicone dielectric grease.

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The Fix, Up Front

1. This is a six-plug job with the upper intake off. The three passenger-side (right) coils are in the open. The three driver-side (left) coils are under the plastic plenum. You are not "doing the easy three and leaving the buried ones for later."
2. Buy Champion 9407 / RER8ZWYCB4 — same plug as Mopar SP149125AD / AE / AF. Qty 6. JL 3.6 is a different Champion number. Confirm your year.
3. New upper-intake gaskets. Reusing the old ones is how you get a vacuum leak and a misfire you just "fixed."
4. Cold engine. Blow the wells out. Hand-start every plug. Thin-wall spark-plug tubes. Drop a plug, nick a tube, you bought an oil leak.
5. 13 ft-lbs on the plugs. Inch-pound wrench at 156 in-lbs. A 10–80 ft-lb wrench is not accurate at 13. Coils 71 in-lbs. Plenum 89 in-lbs. Not 89 ft-lbs.
6. No anti-seize. No Permatex dielectric on the boots. 2012 Wrangler 3.6 factory service manual is explicit on the grease. Plated threads plus anti-seize is how you over-torque a 12 mm plug in an aluminum head.

First time: plan on 2–4 hours. Independent shops quote a "tune-up" and then find the intake. Parts DIY is roughly $80–$130. If the valley is wet with oil when the plenum comes off, stop and do the oil cooler housing — that is the other 3.6 job, not a rear main.

Is This Your Jeep?

Generation	Years	This job?
YJ	1987–1995	No. 4.0 / 2.5. Different plugs, no coil-on-plug.
TJ	1997–2006	No. 4.0 / 2.5. Wires. Different interval.
JK 3.8	2007–2011	No. Champion RE14PLP5, 14 mm thread, 0.050 in gap, ~12 ft-lbs, 30k-mile plugs, spark-plug wires. No intake pull. Stop. This guide is the 3.6.
JK 3.6 Pentastar	2012–2018 (incl. 2018 JK)	Yes. This guide. Champion 9407 / RER8ZWYCB4 / Mopar SP149125AF. Gap 0.043 in (1.1 mm). Plugs 13 ft-lbs.
JL 3.6	2018–present	Same layout: pull the upper intake for the driver bank. Same 13 ft-lbs on the plugs (WAYALIFE JL FSM table: 18 N·m / 13 ft-lbs). Different OEM plug: Champion 9417 / RER8ZWYPB4 / Mopar SP225755AB. Do not order 9407 for a JL and call it done. Confirm the number on the old plug and your year in the catalog.
JT Gladiator 3.6	2020–present	Same rule as JL. Confirm plug PN. Do not mix JK 9407 into a JT without checking.
JL 2.0 / 4xe / 392	—	No. Different engine, different interval (2.0 turbo is typically 60k), different plugs. Stop.

If you don't have a 3.6, this is not your repair.

Shopping a used JK at 80–100k with no plug records? Bank 2 never got done. That's the one under the intake. Add it to the used JK buyer's inspection.

You Cannot Skip the Intake

Every "1-hour spark plug" write-up that never mentions the plenum is describing bank 1 and hoping you don't notice. WranglerForum has been saying the same thing for years: the intake plenum must come off to reach the driver-side plugs.

May 2025, WranglerForum — 2015 JK 3.6 owners still asking which plug and what gap because the owner's manual does not print a Champion number. 2014 JK owner's manual does print the gap: 0.043 in (1.1 mm). January 2025, same forum: people swapping NGK 93175 at a 0.044 pre-gap and Champion iridium from NAPA. June 2024 and May 2024, JLWranglerForums: 2018+ 3.6 owners asking Champion 9417 vs dealer Mopar pricing, and a dealer PDF that told a new JL owner to change plugs at 20k. The 2022 JL owner's manual is 100,000 miles or 10 years for the 3.6. The 20k number is a dealer CMS error. The labor is still the intake.

2018 JL owner on that same interval thread pulled plugs at 85,300 miles and was glad he did not wait for 100k. That is not a license to throw copper plugs in at 30k. Iridium is the design. If you are already in for the oil cooler housing, do the plugs. You already paid the labor.

What the Manual Actually Says

2012 Jeep Wrangler 3.6 factory service manual, spark plug installation (Operation CHARM transcription of the FSM):

• Check and adjust the gap with a gauging tool.
• Do not drop the plug into the well. Electrodes damage.
• Spark-plug tubes are thin-wall. Damage the tube, you get an oil leak.
• Start by hand to avoid cross-threading.
• CAUTION: Spark plug torque is critical and must not exceed the specified value. Overtightening stretches the spark plug shell, reducing heat transfer, resulting in possible catastrophic engine failure.
• Tighten to 17.5 N·m (13 ft. lbs.).

Same book, ignition coil installation:

• Blow dirt off the top of the plug.
• Inspect the coil boot for debris, tears, rips.
• CAUTION: Do not apply a silicone based grease such as Mopar Dielectric Grease to the ignition coil rubber boot. The silicone based grease will absorb into the boot causing it to stick and tear.
• Factory lube is a small 360° bead of Fluostar 2LF, 1–2 mm from the chamfer, not on the chamfer.
• Coil bolt 8 N·m (71 in. lbs.).
• Battery negative nut 5 N·m (45 in. lbs.).

That is the document. Not a forum guess. Not Haynes. 13 ft-lbs is 156 in-lbs. Write it on the fender with a paint pen.

Chrysler also published the 12 mm warning that shows up in every serious Pentastar thread: these are the first Chrysler 12 mm plugs. Over-torque stretches the shell. Heat does not leave the ceramic. Pre-ignition. Pistons. You do not get to "snug plus a quarter turn" on this engine.

The Plug (Do Not Mix Numbers)

JK 2012–2018 3.6 (this guide):

• Champion 9407 / type RER8ZWYCB4
• Mopar SP149125AD, superseded AE, current SP149125AF
• Iridium. 12 mm × 1.25. 5/8 in hex. Gasket seat.
• Gap 0.043 in (1.1 mm) — 2014 JK owner's manual.

JL / JT 3.6: Champion 9417 / RER8ZWYPB4 / Mopar SP225755AB (replaces SP225755AA / 68225755AA). Same 0.043 in gap in Champion's catalog. Same 13 ft-lbs in the JL torque table. Different ceramic/ground. Do not assume a JK box fits a JL.

Amazon path for the JK plug is Champion 9407, sold as a single. Buy six. The listing title talks about Honda. The OE interchange on that same page lists Jeep / Chrysler SP149125AD / AE. Confirm your year in the Amazon garage tool. Amazon's spec table on that listing says "14 mm thread." That field is wrong. This plug is 12 mm. If a listing is actually 14 mm, it is not a 3.6 Pentastar plug.

NGK 93175 / LKR7DIX-11S is the common aftermarket iridium (about 0.044 in pre-gap, which is 1.1 mm). Buy it from NAPA / O'Reilly / RockAuto. Do not buy a "6 pc NGK for Jeep" Amazon bundle from a seller you have never heard of. Counterfeit NGK on marketplaces is a real, repeating problem. You are not pulling this intake twice because a fake electrode melted.

Dealer Mopar if you want the box that says Jeep on it. Same Champion guts, more money.

Check every gap with a wire-style gauge. Not a coin / taper gauge — that bends a fine-wire iridium tip. Champion 9407 often ships closer to 0.039 in. The FSM says check and adjust. Open the gap by moving the ground strap, not the center electrode.

Parts You Actually Need

Plugs (pick one path):

• Champion Iridium 9407 / RER8ZWYCB4 — qty 6. JK 2012–2018 3.6. Confirm garage fitment. Not the JL 9417.
• Mopar SP149125AF from a dealer / Mopar house — current OE for the JK 3.6. No verified genuine-Mopar Amazon listing used here; don't fake one.
• JL 3.6: Champion 9417 or Mopar SP225755AB from a dealer or NAPA. Do not order 9407 for a JL.

Gaskets:

• Fel-Pro MS 97204 — upper and lower intake set. You only pull the upper for plugs. Use the six upper gaskets. Leave the lower set in the bag unless you are already in the valley for the oil cooler. Confirm Wrangler 3.6 in the Amazon garage tool. Mopar upper-only is 5184562AC from a dealer if you want OE singles.

Optional while the plenum is off: Mopar PCV for your year from the dealer. T25. 35 in-lbs (4 N·m). Do not reuse a collapsed valve. If the valley is a puddle of oil, that is not the PCV — that is the oil cooler housing.

Skip: Autolite "equivalent" junk, no-name 6-packs that copied the Mopar number, anti-seize, and a tube of Permatex dielectric for the boots.

Tools You Actually Need

You already have 8 mm and 10 mm sockets, extensions, and a ratchet. The two things people skip are the inch-pound wrench and a real spark-plug socket.

• EPAuto 1/4" click torque wrench, 20–200 in-lbs — plugs at 156 in-lbs, coils at 71, plenum at 89, battery at 45, PCV at 35. A 10–80 ft-lb wrench is not accurate at 13 ft-lbs. This is the wrench.
• TEKTON 3/8" drive × 5/8" spark-plug socket, SHD15016 — rubber grommet, thin wall. The EPAuto 1/4" wrench includes a 1/4-to-3/8 adapter. Magnetic sockets also work. A 12-point "close enough" socket is how you round a 12 mm plug in a hole you cannot see.
• 8 mm (plenum bolts and most coil bolts) and 10 mm (intake-tube bolts, some brackets). Look at the head before you start.
• 3 in and 6 in extensions. Swivel if you need it. Do not side-load the plug.
• Wire-style gap tool that includes 0.043 / 0.044 in. Not a coin gauge.
• Compressed air or a blow gun. Shop vac. The FSM starts with blowing the well out.
• Painter's tape or clean rags for open intake ports if you go far enough to see them. You should not have the lower intake off for plugs-only.
• Battery disconnect. Drain pan is not required. Flashlight is.

Torque Specs (Do Not Guess)

JK numbers from the 2012 Jeep Wrangler 3.6 factory service manual (spark plug and coil install) plus the 2017 JK 3.6 FSM intake table already used on this site for the oil-cooler job. JL plug torque from the WAYALIFE JL FSM-derived table: 18 N·m / 13 ft-lbs — same 13. Inch-pounds unless noted.

Fastener	Torque	Notes
Spark plugs (M12, 3.6)	13 ft-lbs (17.5 N·m / 156 in-lbs)	2012 JK FSM. Do not exceed. Inch-pound wrench. JL table: 18 N·m / 13 ft-lbs.
Ignition coil bolt (M6)	71 in-lbs (8 N·m)	2012 JK FSM. Start by hand.
Upper intake manifold (M6, 7 bolts)	89 in-lbs (10 N·m)	Composite plenum. Center out, then repeat. Not 89 ft-lbs.
Upper intake support-bracket nuts (M6)	89 in-lbs (10 N·m)	Same 2017 JK FSM table.
Throttle body (M6), if you pulled it	62 in-lbs (7 N·m)	New gasket if it comes off.
PCV valve (M5 T25), optional	35 in-lbs (4 N·m)	2017 JK FSM. Do not gorilla plastic.
Negative battery cable nut	45 in-lbs (5 N·m)	2012 JK FSM coil-install wrap-up.
Intake-tube 10 mm bolts / hose clamps	Snug	No factory number cited here. Don't twist the plastic airbox neck.
JK 3.8 spark plugs	Not this job	Different engine. Commonly cited ~12 ft-lbs / 0.050 in. Do not use 13 ft-lbs on a 3.8 because you read this page.

Plenum sequence (JK 3.6, same as the oil-cooler article): start all bolts by hand. Snug center, then out. Torque to 89 in-lbs. Repeat the sequence so the outer bolts don't unload the middle. If a bolt gets heavy early, back it out. You are threading into a plastic manifold and aluminum below it.

Job Sequence

Cold engine. Level ground. Disconnect the negative battery cable.

Bank 1 — passenger side, no intake yet

1. Engine cover off. You should see three coils on the right head, each with a connector and one bolt.
2. Unclip the coil connector. 8 mm (sometimes 10 mm — look) on the coil bolt. Twist the coil and pull straight up. Keep coils in order if you are reusing them.
3. Blow the well out. Compressed air. Dirt in an open cylinder is an engine.
4. 5/8 in spark-plug socket, extension, no side load. Break it loose. Spin it out by hand once it is free. Look at the old plug: tan insulator is normal. Oil on the threads is a tube or valve-cover problem. White blistering is lean / overheat. Keep that plug; it is data.
5. Check the new plug gap. 0.043 in (1.1 mm). Wire gauge. Adjust the ground strap only.
6. Hand-start. Extension only, no ratchet, until it seats. If it binds, back out. Cross-thread in aluminum is a helicoil.
7. Torque to 13 ft-lbs / 156 in-lbs. Stop at the click. The FSM's failure mode is a stretched shell, not a loose plug.
8. Inspect the coil boot. Debris out with a lint-free cloth. Tears = replace the coil or the boot, don't glue it.
9. No silicone dielectric grease. If you have Fluostar 2LF (FSM) or later Chrysler Molykote G-5008 (dealer, Mopar 68364292AA — that TSB is written around 2.4L boots, same "only this grease" warning), a 1–2 mm bead inside the boot, not on the chamfer. If you don't have that tube, install the boot dry. Do not substitute Permatex.
10. Coil on with a twist. Bolt to 71 in-lbs. Connector until it clicks. Repeat for the other two passenger plugs.

Bank 2 — pull the plenum

11. Intake tube off: IAT / temp sensor on the tube, both clamps, two 10 mm bolts at the shroud. Unclip the small hose that rides on those bolts. Set the tube aside.
12. Label vacuum lines and electrical connectors on the upper intake. Photo with your phone. Heater-line bracket (10 mm nuts), breather hoses, throttle-body connector, any foam insulator pad.
13. Upper-intake fasteners are 8 mm. Several are long and stay captive in the plenum. The rear one hides toward the firewall — pull the heat-pad clips if you cannot see it. Do not pry on the plastic.
14. Plenum up and off. Foam over the driver-side coils comes with it. You should now see three more coils. Same plug procedure as bank 1: blow, pull, gap, hand-start, 13 ft-lbs, coils 71 in-lbs.
15. Optional: PCV while you can reach it. New valve. 35 in-lbs.
16. Look in the valley. Dry aluminum = keep going. A puddle of oil = oil cooler housing, and you are already most of the way into that job. Do not button the intake up over a wet valley and hope.

Plenum back on

17. Pull the old upper gaskets. Seats clean and dry. No RTV unless a gasket maker specifically calls for it — Fel-Pro's sheet for this set is clean and dry.
18. New upper gaskets in the lower-intake grooves. Plenum down square. Start every bolt by hand.
19. Torque upper intake to 89 in-lbs, center out, then the sequence again. Support-bracket nuts 89 in-lbs.
20. Tube, sensors, heater bracket, foam, engine cover. Battery cable 45 in-lbs.

Start it. Idle should be smooth. No whistle at the plenum (vacuum leak). Heat-cycle once, then recheck for a coil that did not click and a plenum bolt that backed off.

What NOT to Do

Don't do three plugs and call it a tune-up. Bank 2 is why this job has a reputation.

Don't use a foot-pound wrench "at about 13." Use 156 in-lbs on an inch-pound wrench.

Don't put anti-seize on Champion / NGK plated threads. You just turned 13 ft-lbs into 16. Aluminum head. 12 mm plug. FSM didn't ask for it.

Don't smear silicone dielectric grease in the coil boots. 2012 Wrangler FSM: it soaks into the rubber, the boot sticks, the boot tears. Dry, or Fluostar 2LF / Molykote G-5008 from a dealer.

Don't drop the plug in the well and then ratchet it. Electrode is now garbage. Tubes are thin-wall. Oil down the tube is the next leak you get to explain.

Don't reuse upper-intake gaskets. A $27 Fel-Pro set is cheaper than chasing P0171 / a whistle for a month.

Don't order Champion 9407 for a JL 3.6. 9417 / SP225755AB. Don't order NGK 5107 / LZTR7AIX-13 either — that's a 14 mm HEMI plug.

Don't mix 3.8 parts onto a 3.6. Wires, 14 mm, 0.050 in, 12 ft-lbs. Different engine.

Don't ignore a wet valley. That's the oil cooler housing. The plugs will not fix oil on the exhaust.

Don't pry the iridium center wire to "set the gap." Move the ground strap with a wire tool.

After the Repair

Misfire codes (P0300–P0306) may need a drive cycle to clear. If a single cylinder comes back immediately, that coil didn't seat, that plug is still at 0.039 in, or you pinched a gasket on that runner.

A whistle or rough idle that showed up after the job is the plenum. Back to 89 in-lbs, then gaskets. Don't keep topping it with a can of sea foam.

Next oil change: glance at the passenger coils. White dust around a boot is a boot that is leaking spark to the valve cover. Replace that coil/boot. Don't wait for a flash on the highway.

If you stopped because the valley was wet, finish the housing. Putting new plugs in an engine that is dumping oil on the exhaust is not a repair.

Quick Reference

1. JK 3.6 (2012–2018) — Champion 9407 / RER8ZWYCB4 / Mopar SP149125AF · gap 0.043 in (1.1 mm)
2. JL 3.6 — Champion 9417 / RER8ZWYPB4 / Mopar SP225755AB · same 13 ft-lbs · confirm PN
3. Passenger bank open · driver bank under the upper intake · new upper gaskets
4. Plugs 13 ft-lbs (17.5 N·m / 156 in-lbs) · coils 71 in-lbs · plenum 89 in-lbs · PCV 35 in-lbs · battery 45 in-lbs
5. Blow the wells · hand-start · no anti-seize · no silicone dielectric on the boots
6. Thin-wall tubes — don't ding them
7. Wet valley = oil cooler housing, not a "tune-up"

This is a 2–4 hour intake-and-plug job, not a 30-minute coil swap. Pull the plenum, use the inch-pound wrench, put the right Champion in. You'll stop throwing misfires at 90k and stop paying a dealer to "find" bank 2.