P0302 on 2020-2025 Jeep Wrangler: Cylinder 2 Misfire Causes and Fixes

What's Unique About the 2020-2025 Jeep WRANGLER

For the 2020-2025 Jeep Wrangler (JL), a P0302 code can point to common ignition component failures, 🎬 Watch: A quick guide to understanding the P0302 code. but it can also be linked to more specific platform issues. The 3.6L Pentastar V6 engine, used in many Wranglers, has a known history of valvetrain problems, such as worn rocker arms or lifters that can lead to misfires. While this was more common on earlier JK models, it still occurs on the JL and is often preceded by a distinct ticking sound from the engine. Additionally, TSB #18-003-23 specifically addresses misfires, including P0302, that occur only when the vehicle is operated in 4WD-LO, which is resolved by a PCM software update, not a mechanical repair. For some 2021 models, TSB 09-013-20 REV. A was issued for factory-installed spark plugs that were prone to internal cracking, causing misfires.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle. 👇

Symptoms You May Notice

• Rough or shaky idle
• Engine hesitation or stumbling during acceleration
• Noticeable loss of power
• Flashing or solid Check Engine Light
• Reduced fuel economy
• Engine stalling
• Unusual odor from the exhaust

Most Likely Causes

1. Faulty Ignition Coil 🔴 High Probability → Shop Ignition Coil Coil-on-plug systems are common points of failure due to constant heat and vibration in the engine bay. This is a frequent fix reported by owners.
   How to confirm: Swap the ignition coil from cylinder #2 with an adjacent cylinder (e.g., cylinder #4). Clear the codes and drive the vehicle. If the code changes to P0304, the ignition coil is faulty. This is the most common DIY diagnostic step.
   Typical fix: Replace the faulty ignition coil. It is often recommended to replace the corresponding spark plug at the same time.
   Est. part cost: $40-$90
2. Worn or Defective Spark Plug 🔴 High Probability → Shop Spark Plug Spark plugs are a regular maintenance item. Specifically for 2021 models with the 3.6L engine, TSB 09-013-20 REV. A was issued due to a manufacturing defect causing internal cracks in the spark plugs, leading to misfires.
   How to confirm: Remove the spark plug from cylinder #2 and inspect it for wear, damage, or carbon fouling. You can also swap it with another cylinder's spark plug to see if the misfire follows. Given the TSB, even a visually okay plug could be internally faulty on affected models.
   Typical fix: Replace the spark plug. It's best practice to replace all spark plugs at the same time. Per TSB 09-013-20, if a misfire is found on an affected vehicle, all six plugs must be replaced.
   Est. part cost: $10-$30 per plug
3. Clogged or Faulty Fuel Injector 🟡 Medium Probability → Shop Fuel Injector
   How to confirm: Listen to the injector with a mechanic's stethoscope to check for a consistent clicking sound. For a more definitive test, you can swap the injector with another cylinder, but this is more labor-intensive. A professional can perform a fuel injector balance test.
   Typical fix: First, try a quality fuel injector cleaner like Techron or Seafoam. If that fails, the injector will need to be professionally cleaned or replaced.
   Est. part cost: $70-$150
4. Mechanical Engine Issue (Valvetrain) ⚪ Low Probability The 3.6L Pentastar engine has a documented history of valvetrain issues, including worn rocker arm bearings that seize and damage the camshaft lobes. While more common on the previous JK generation, this failure still occurs on JLs and can cause a persistent P0302 after ignition parts are ruled out.
   How to confirm: Listen for a rhythmic, metallic ticking sound from the top of the engine, especially the driver's side. A definitive diagnosis requires a compression test and a cylinder leak-down test. Visual inspection of the camshafts and rocker arms by removing the valve cover is often necessary.
   Typical fix: Requires replacement of the worn components, such as all rocker arms and lifters for the affected bank, and potentially the camshaft if it is damaged. This is a complex and expensive repair.
   Est. part cost: $500-$2000+

Rare But Worth Checking

• Wiring Harness Issue: A video on a 3.6L Wrangler showed a misfire caused by a poorly seated pin in a wiring harness connector near the valve cover, causing an intermittent connection to the coil. Wiggling the harness while the engine is running may reveal the issue.
• Vacuum Leak: A leak in the intake manifold gasket or a vacuum hose can lean out the air-fuel mixture and cause misfires. This would typically be accompanied by other codes like P0300 (multiple misfires). A smoke test is the most effective way to find a leak.
• Faulty VVT Solenoid: On the 3.6L engine, a failing Variable Valve Timing (VVT) solenoid can cause a misfire. An owner of a platform-mate (Dodge Durango) with a persistent P0302 that wasn't fixed by plugs or coils solved the issue by swapping the front VVT solenoids between the driver and passenger side banks. The misfire code moved to cylinder #1 (P0301), confirming the solenoid was the bad part.

Diagnosis Steps

1. Read the code using an OBD-II scanner and confirm P0302 is present. Note any other codes.
2. Clear the codes and test drive to see if the code returns immediately.
3. Listen for a rhythmic ticking noise from the driver's side of the engine bay, which could indicate a valvetrain issue (rocker arm/lifter).
4. If the code returns, swap the ignition coil from cylinder #2 (driver's side, front) with another cylinder (e.g., #4). Clear the codes and drive again. If the code changes to P0304, the coil is bad.
5. If the code remains P0302, swap the spark plug from cylinder #2 with the one from the cylinder you just moved the good coil to. If the code now follows the spark plug, the plug is bad.
6. If the misfire is still on cylinder #2, inspect the wiring and connector for the ignition coil and fuel injector for any damage or loose connections.
7. Check the fuel injector on cylinder #2. Listen for a steady clicking sound. Consider swapping it with another cylinder if you have the mechanical skill.
8. If the above steps do not identify the issue, perform a compression test on cylinder #2 to check for mechanical engine problems like bad rings, valves, or a head gasket leak.
9. If compression is low, perform a cylinder leak-down test to pinpoint the source of the compression loss.

Parts You'll Likely Need

• Ignition Coil (OEM #68223569AD (for 3.6L V6)) — This is one of the most frequent failure points for a single-cylinder misfire. Heat and vibration cause the internal windings to fail over time.
  Trusted brands: Mopar, NGK, Delphi
  OEM price range: $60-$100
  Aftermarket price range: $40-$90
• Spark Plug (OEM #SP225755AB (for 3.6L V6)) — Spark plugs are a standard wear item. For some 2021 models, they were defective from the factory and are the direct cause of the misfire per TSB 09-013-20 REV. A.
  Trusted brands: Mopar, NGK, Champion
  OEM price range: $20-$40
  Aftermarket price range: $10-$30
• Fuel Injector — A clogged or electrically failed fuel injector will prevent the correct amount of fuel from entering the cylinder, leading to a misfire.
  Trusted brands: Mopar, Bosch
  OEM price range: $120-$200
  Aftermarket price range: $70-$150

Related Codes That Often Appear With This One

• P0300 — If the condition causing the misfire on cylinder 2 is also affecting other cylinders intermittently, a P0300 (Random/Multiple Cylinder Misfire) code may also be set.
• P0301, P0303, P0304, P0305, P0306 — These codes indicate misfires in other specific cylinders. Seeing them alongside P0302 points to a systemic issue like a vacuum leak, low fuel pressure, or a broader engine problem. Multiple misfire codes are specifically mentioned in TSBs like 09-013-20 REV. A (faulty plugs) and 18-003-23 (4WD-LO issue).

Technical Service Bulletins (TSBs) & Recalls

• 09-011-25: Lists P0302 as a potential DTC for 2025 engine issues.
• 1805223: Lists P0302-00 as a possible DTC for 2023 electrical system issues.
• 18-158-22: Lists P0302-00 as a possible DTC for 2022 fuel system issues.
• 1400322REVA: Lists P0302 as a potential DTC for 2021 fuel system issues.
• 18-003-23: Notes P0302-00 can occur on 2020 models with the MIL illuminating only during 4WD-LO operation.

Platform-Specific Known Issues

• Misfire in 4WD-LO Only (Software Issue): TSB #18-003-23 for 2020 models notes that P0302 can occur specifically when the vehicle is operated in 4WD-LO. This is not a mechanical problem but a software calibration issue that can be fixed by a dealer with a PCM update.
• Defective Factory Spark Plugs (2021 Models): → Shop Spark Plug TSB #09-013-20 REV. A was issued for some 2021 Wranglers due to a batch of factory-installed spark plugs that were prone to internal cracking, causing single or multiple cylinder misfires. The fix is to replace all six spark plugs.

Mechanic-Grade Diagnostic Values

• Ignition Coil Primary Resistance (3.6L V6) — expected: 0.56 - 0.68 ohms. Failure: A reading outside of this range indicates a faulty coil.
• Ignition Coil Secondary Resistance (3.6L V6) — expected: 6.0K - 9.6K ohms. Failure: A reading outside of this range suggests an internal coil failure.
• Fuel Pressure (Running at Idle) — expected: ~50-55 PSI. Failure: Significantly lower pressure indicates a weak fuel pump or clogged filter.
• Spark Plug Gap — expected: 0.028 - 0.032 inches. Failure: An incorrect gap can lead to a weak or inconsistent spark.

Hidden / Shadow Codes Worth Checking

• Mode $06 Misfire Counter: This is not a formal trouble code, but a diagnostic data parameter. Advanced scan tools can access Mode $06 data to view the raw misfire count for each cylinder, even for misfires not frequent enough to set a P0302 code. This can help confirm an intermittent issue on cylinder 2. (see via An advanced OBD-II scanner or an app with live data capabilities (like JScan) that can display Mode $06 test results.)

Scan Tool Commands That Help

• WiTech (dealer), Autel, JScan, or other advanced scanner: Cylinder Contribution / Power Balance Test — This function allows the scanner to electronically disable one cylinder at a time and measure the corresponding drop in engine RPM. If disabling cylinder #2 results in little or no RPM drop compared to other cylinders, it confirms that cylinder #2 is not contributing power, pinpointing the misfire without swapping parts.

Wiring & Ground Locations

• Cylinder #2 Coil/Injector Harness Connector — On the 3.6L V6, there is a large, multi-pin engine harness connector located on the passenger side, near the valve cover.. A documented failure involves a poorly seated pin (specifically pin 5, a blue/tan wire on a JK model) within this connector, causing an intermittent connection to the cylinder 2 ignition coil. Wiggling this connector with the engine running can expose the fault.
• G914B — A ground point for the injector harness on the 3.6L engine.. A loose or corroded ground at this location can cause erratic behavior for the fuel injectors, potentially leading to a misfire code.
• G905A — A ground point for the main dash harness.. While less direct, poor grounding here can introduce electrical noise or voltage issues that may affect PCM calculations and sensor readings related to the engine.

Real Owner Repair Stories

• JK-Forum.com user (2015 Jeep Wrangler Unlimited Sport, 3.6L V6, 53k miles) — Solid check engine light with code P0302.
  ❌ Tried (didn't work) Replaced spark plug on cylinder 2, Replaced ignition coil on cylinder 2, Swapped coil and plug from cylinder 2 to cylinder 4 (code remained P0302), Swapped fuel injector from cylinder 2 to cylinder 4 (code remained P0302)
  ✅ What actually fixed it The dealership found the cylinder had poor compression. The cylinder head was repaired or replaced under the powertrain warranty, which resolved the misfire.
• YouTube video by Konrad Chmielewski (2014 Jeep Wrangler, 3.6L V6) — Intermittent P0302 and P2305 (Ignition Coil 2 Secondary Circuit) even after replacing the coil.
  ❌ Tried (didn't work) Replacing the ignition coil on cylinder 2.
  ✅ What actually fixed it The root cause was a poorly seated female pin for the cylinder 2 coil control wire (pin 5, blue/tan) inside the large engine harness connector on the passenger side valve cover. The pin had receded into the connector, causing a poor connection. Reseating the pin properly fixed the intermittent misfire.
• Reddit user in r/Wrangler (2018 Jeep Wrangler JLUR, 3.6L V6, manual transmission) — P0302 misfire occurs only when the engine is revved above ~3800 RPM. Once triggered, the engine runs rough until it is shut off and restarted. Drives normally if kept at lower RPM.
  ❌ Tried (didn't work) No parts were tried; the user was seeking diagnostic advice based on the specific symptom.
  ✅ What actually fixed it The owner suspected an issue with the Variable Valve Lift (VVL) solenoid for that cylinder, preventing the valvetrain from switching to the high-lift cam profile at higher RPMs. While not a confirmed fix, this specific symptom points directly toward a VVL system diagnosis rather than a typical ignition or fuel problem.

"I Checked Everything" — The Actual Cause

• In a case documented on a 3.6L Wrangler, a persistent P0302 that was not resolved by swapping plugs or coils was ultimately traced to a single pin that had backed out of its seat within a large engine harness connector. A smoke test would have shown no leaks, and standard component swaps would point away from the ignition system, but the actual cause was an intermittent electrical connection that only failed under certain conditions of vibration or temperature. The fix was to identify and properly reseat the wire's pin in the connector.

When the Usual Fixes Don't Work

• While the most common causes for a P0302 are ignition-related, there are confirmed owner experiences where the code persisted after extensive parts swapping. In one case involving a 2015 Wrangler, the owner replaced the spark plug and coil, then swapped both components to another cylinder, and even swapped the fuel injector, all with no effect—the misfire code remained P0302. The ultimate diagnosis was an internal engine failure causing low compression in cylinder #2, which required dealership repair of the cylinder head. This serves as a strong reminder that if common, easy fixes do not resolve the issue, a mechanical compression test is a critical next step before replacing more parts.

OEM Part Supersession History

• 68223569AB, 68223569AC → 68223569AD — Standard part revision and improvement by the manufacturer.
  Heads up: The newer part number (68223569AD) is the correct and backward-compatible service replacement for the earlier versions on the 3.6L Pentastar engine.

Model Year Variations Within This Range

• 2020: A software issue can cause a P0302 misfire specifically when operating in 4WD-LO. This is unique to a TSB for this model year and is fixed with a PCM update, not parts.
• 2021: A specific batch of factory-installed spark plugs was known to be defective and cause misfires. TSB 09-013-20 REV. A addresses this, making spark plugs the primary suspect for P0302 on these vehicles.
• 2020-2025 (3.6L V6 vs 2.0L I4): On the 3.6L V6, cylinder #2 is on the driver's side, and accessing its ignition coil requires removing the upper intake manifold. On the 2.0L I4, cylinder #2 is the second from the front, and its coil is immediately accessible without major disassembly, significantly affecting labor time.