P0305 on 2016-2023 Jeep Wrangler: Cylinder 5 Misfire Causes and Fixes

What's Unique About the 2016-2023 Jeep WRANGLER

For the Jeep Wrangler, especially models with the common 3.6L Pentastar V6, a P0305 code is more than just a routine ignition issue. 🎬 Watch: A quick overview of diagnosing a Cylinder 5 misfire. This engine family has a well-documented weakness in its valvetrain, specifically with rocker arm bearings that can fail. This failure causes the rocker arm to seize or wear excessively, which in turn grinds down the corresponding lobe on the camshaft. The result is a valve that no longer opens sufficiently, causing a loss of compression and a persistent misfire. This is often preceded by a ticking noise known as the 'Pentastar tick.' While you should always check the basics like spark plugs and coils first, a P0305 on this particular vehicle warrants a closer listen for that ticking sound, as it could signify a more involved mechanical repair is needed.

Diagnostic Flowchart

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

Generation note: This range covers the end of the Jeep Wrangler JK generation (2016-2018) and the current JL generation (2018-2023). The P0305 code is most relevant to the 3.6L Pentastar V6 engine found in both generations, as well as the 3.0L EcoDiesel V6 and 6.4L HEMI V8 found in the JL. The 2.0L 4-cylinder turbo engine offered in the JL cannot generate this code as it only has four cylinders.

Symptoms You May Notice

• Check Engine Light is on (solid or flashing)
• Rough or shaking idle. [TSB #09-011-25]
• Engine hesitation or stumbling on acceleration.
• Noticeable loss of engine power.
• Ticking or tapping noise from the top of the engine, specifically the passenger side, that may increase with RPM. [TSB #09-011-25, 17]
• Smell of unburnt fuel from the exhaust.
• In severe cases, white exhaust smoke with a sweet smell, indicating a coolant leak into the cylinder. [ODI #11688993]

Most Likely Causes

1. Failed Rocker Arm and/or Lifter 🔴 High Probability The 3.6L Pentastar V6 has a known design issue with the needle bearings in the rocker arms, which can fail, seize, and destroy the camshaft lobe, causing a misfire. TSB #09-011-25 specifically links misfire codes with valvetrain noise. This is the most discussed major failure for this code on Wrangler forums.
   How to confirm: Listen for a distinct ticking or tapping sound from the passenger side of the engine where cylinder 5 is located. The sound may be more pronounced on a cold start but is often present at idle. A definitive diagnosis requires removing the passenger-side valve cover for a visual inspection of the rocker arms and camshaft lobes for wear or damage. A worn lobe will be visibly ground down compared to the others.
   Typical fix: Replace all rocker arms and hydraulic lifters on the affected cylinder head (passenger side for cylinder 5). The camshaft must also be replaced if any lobes are scored or worn. Many owners and shops recommend replacing them on both heads as a preventative measure.
   Est. part cost: $200-$600 for a full set of lifters, rockers, and potentially a camshaft.
2. Faulty Ignition Coil 🟡 Medium Probability
   How to confirm: Swap the ignition coil from cylinder 5 with another cylinder (e.g., cylinder 3, which is also on the passenger side). Clear the codes and drive the vehicle. If the code changes to P0303, the ignition coil is the faulty part.
   Typical fix: Replace the single faulty ignition coil. Many owners choose to replace all plugs and coils on the bank at the same time, especially on higher mileage vehicles.
   Est. part cost: $40-$100
3. Worn or Fouled Spark Plug 🟡 Medium Probability
   How to confirm: Remove the spark plug from cylinder 5. Inspect it for signs of wear (worn electrode), carbon fouling, oil, or coolant contamination. A coolant-fouled plug will appear white and clean, indicating a more serious issue like a head gasket leak.
   Typical fix: Replace the spark plug. It is best practice to replace all spark plugs at the same time, as they are a maintenance item.
   Est. part cost: $10-$25
4. Clogged or Faulty Fuel Injector ⚪ Low Probability Injectors can fail electrically or become clogged over time. The P0205 code (Injector Circuit/Open - Cylinder 5) often accompanies P0305 when the injector is the root cause.
   How to confirm: After ruling out spark and coil, you can test the fuel injector's resistance with a multimeter. A good injector on a 3.6L Pentastar should read around 12 ohms. A significantly higher reading (e.g., 30-60 ohms) or an open circuit indicates a failed injector. This test can be done without removing the intake manifold for the passenger-side cylinders (1, 3, 5). If resistance is good, you can swap the injector with another cylinder, but this is more labor-intensive.
   Typical fix: Replace the faulty fuel injector. Some owners report success running a quality fuel system cleaner first.
   Est. part cost: $50-$150

Rare But Worth Checking

• Cracked Cylinder Head / Failed Head Gasket: While less common than the rocker arm issue on later models, this is a severe problem. An owner of a 2018 Wrangler reported recurrent P0305 along with coolant loss, white smoke, and overheating, classic signs of a head or gasket failure. [ODI #11688993] If you have these symptoms, this should be investigated immediately.
• Low Cylinder Compression: Internal engine damage such as a burnt valve or worn piston rings can cause low compression, leading to a misfire. A compression test is needed to diagnose this. A wiped camshaft lobe from a failed rocker arm will also result in low compression readings for that cylinder.

Diagnosis Steps

1. Read the code with an OBD-II scanner to confirm P0305 and check for any other codes.
2. Listen carefully to the engine at idle and with light revs, focusing on the passenger side (right side) valve cover for any ticking or tapping sounds.
3. If no ticking is heard, start with ignition basics. Swap the ignition coil from cylinder 5 to cylinder 3. Clear the codes. If the misfire moves to P0303, replace the bad coil.
4. If the misfire stays on cylinder 5, remove and inspect the spark plug for wear, damage, or fouling.
5. If spark and coil are good, test the fuel injector. Unplug the connector for the cylinder 5 injector and measure the resistance across its two pins with a multimeter. A good injector should read around 12-14 ohms. A significantly different reading indicates a bad injector.
6. Check coolant levels and inspect the oil for a milky appearance. Check the old spark plug for signs of coolant. This can point to a head gasket issue. [ODI #11688993]
7. If a ticking noise IS present, the most probable cause is a failed rocker arm/lifter and likely a damaged camshaft. This requires removing the valve cover for inspection. Look for loose/broken rocker arms and worn-down camshaft lobes.
8. Perform a compression test on cylinder 5 to rule out issues with valves or piston rings. A low reading can confirm a mechanical problem like a worn cam lobe or bad valve. Unusually high compression (e.g., 240 PSI when others are 170 PSI) can indicate excessive carbon buildup or oil in the cylinder.

Parts You'll Likely Need

• Rocker Arm and Lifter Kit (OEM #Rocker Arm: 5184296AH, Lifter: 5184332AA) — This is the most common major failure point on the 3.6L Pentastar engine that directly causes a mechanical misfire like P0305. The part number 5184296AH is an updated rocker arm design intended to be more durable than previous versions.
  Trusted brands: Mopar, Mahle, Melling
  OEM price range: $250-$400
  Aftermarket price range: $150-$300
• Ignition Coil (OEM #5149168AH) — A standard failure item for any engine that will cause a single-cylinder misfire.
  Trusted brands: Mopar, NGK, Denso, MSD
  OEM price range: $50-$80
  Aftermarket price range: $30-$60
• Spark Plug (OEM #SP142582AC) — Spark plugs are a regular maintenance item and can cause misfires when worn or fouled.
  Trusted brands: Champion, NGK
  OEM price range: $15-$25
  Aftermarket price range: $8-$15
• Intake Camshaft (Right/Passenger Side) — Often required if a failed rocker arm has worn down the camshaft lobe, which is a very common occurrence with this issue.
  Trusted brands: Mopar
  OEM price range: $250-$350
  Aftermarket price range: $150-$250

Related Codes That Often Appear With This One

• P0300 — If the misfire becomes more widespread due to a systemic issue like a failing camshaft or major vacuum leak, a P0300 (Random/Multiple Cylinder Misfire) may appear alongside P0305. [TSB #18-021-16 REV. B]
• P0301, P0303 — If the entire passenger side bank is affected by a worn camshaft or other issue, you may see misfire codes for cylinders 1 and 3 as well. [TSB #09-011-25]
• P0205 — This code for 'Cylinder 5 Injector Circuit/Open' points directly to an electrical fault with the fuel injector for cylinder 5. If you see P0205 alongside P0305, the fuel injector is the most likely culprit.

Technical Service Bulletins (TSBs) & Recalls

• Bulletin #09-011-25: Links P0301-P0306 misfire codes with customer complaints of rough idle and valvetrain noise.
• Bulletin #18-158-22: Lists P0305-00 - Cylinder 5 Misfire as a potential fault code related to a software update.
• Bulletin #1400322REVA: Connects P0305 with rough idle symptoms.
• Bulletin #18-003-23: Notes that P0305-00 can occur specifically when the vehicle is in 4WD-LO mode.
• Bulletin #09-002-17: While focused on the left cylinder head (cylinders 2,4,6), this TSB is part of the broader narrative of Pentastar valvetrain issues and warranty extensions for some model years.

Platform-Specific Known Issues

• Valvetrain Failure: The 3.6L Pentastar V6 is widely known for premature failure of the rocker arm needle bearings, which can seize, score the camshaft, and cause a persistent ticking noise and misfire codes like P0305. TSB #09-011-25 acknowledges the link between misfire codes and valvetrain noise.

Mechanic-Grade Diagnostic Values

• Fuel Injector Resistance (3.6L Pentastar) — expected: 12.0 - 14.5 ohms. Failure: A significantly higher reading (e.g., 30-60+ ohms) or an open/infinite reading indicates a failed injector coil winding.
• Ignition Coil Primary Resistance (3.6L Pentastar) — expected: Approximately 0.46 - 0.57 ohms. Failure: A reading outside of this narrow range suggests the coil's primary winding is faulty.
• Ignition Coil Secondary Resistance (3.6L Pentastar) — expected: Approximately 9.5 - 15.70 kOhms. Failure: A reading outside this range indicates a fault in the secondary winding.
• Live Misfire Count (Mode 6 / wiTECH) — expected: Zero or very few counts on a healthy cylinder at idle and under load.. Failure: A rapidly increasing number of misfire counts on cylinder 5 confirms the misfire is actively occurring.

Scan Tool Commands That Help

• wiTECH (Chrysler/Jeep Dealer Tool): OBDII Monitors -> 'Which cylinder is misfiring' — This function provides live misfire counts for each individual cylinder, which is invaluable for confirming which cylinder is at fault, especially when only a P0300 (random misfire) is present or to see the severity of the P0305 misfire in real-time.
• wiTECH (Chrysler/Jeep Dealer Tool): Misc. Functions -> 'Clear Mis-fire TLC' — This function can be used to reset the 'Tooth Learn Correction' for the crankshaft position sensor after repairs have been made, which can sometimes help the PCM more accurately detect misfires.

Wiring & Ground Locations

• Main Engine/Battery Ground — The main negative battery cable connects to a stud on the chassis/body near the battery tray and fuse box (TIPM). A separate ground strap typically runs from the engine block to the firewall or chassis.. A poor engine ground can cause a weak spark or erratic sensor readings, leading to misfires. While not specific to cylinder 5, it's a fundamental check for any electrical or ignition-related DTC.
• G905A / G906A / G907A (JL Wrangler) — These are primary dash and instrument panel grounds located in the passenger and driver footwell areas, often behind the kick panels.. While not directly for the ignition coil, these grounds are critical for the Powertrain Control Module (PCM) and other interior modules. A fault here could cause a wide range of bizarre electronic issues, though it's less likely to cause a single-cylinder misfire.
• Injector Harness Ground (JL Wrangler) — The injector harness has its own ground points, identified as G914B and G927A in wiring diagrams, typically located on the engine itself.. A bad ground specific to the injector harness could cause issues with fuel injector operation, potentially leading to a misfire code. If a P0205 (injector circuit) code is also present, this ground should be inspected.

Real Owner Repair Stories

• Reddit user in r/JeepJK (2016 Jeep Wrangler Rubicon Unlimited, 117k miles) — P0305 misfire code, tapping engine noise.
  ❌ Tried (didn't work) Initial diagnosis
  ✅ What actually fixed it Dealer teardown found worn camshafts on both sides, collapsed lifters, and worn rocker arms. The final repair involved replacing all four camshafts (intake and exhaust for both banks), all lifters, and all rocker arms.
• Reddit user in r/Jeep (2014 Jeep Wrangler, 104k miles) — Persistent P0305 code over the course of a year.
  ❌ Tried (didn't work) Replacing spark plugs (worked temporarily), Replacing coil packs and spark plugs again (worked temporarily)
  ✅ What actually fixed it An engine teardown revealed a 'wiped cam' lobe. The final fix was replacing the camshaft, rocker arms, and checking valve springs and clearances under warranty.
• Jeep Wrangler JK Forum user (Jeep Wrangler JK) — P0305 code and an audible ticking noise from the top of the engine.
  ❌ Tried (didn't work) Initial diagnosis
  ✅ What actually fixed it The owner identified a bad rocker arm on the passenger side (cylinders 1,3,5). After replacing the faulty rocker arm, the ticking noise was gone and the check engine light did not return after 50 miles of driving.

OEM Part Supersession History

• 5184296AD, 5184296AE, 5184296AF, 5184296AG → 5184296AH — The rocker arm for the 3.6L Pentastar has been updated multiple times. The 'AH' revision is the latest version, believed to have improved bearings to address the common ticking and failure issue that leads to camshaft damage.

Model Year Variations Within This Range

• 2016-2018 (JK) vs 2018-2023 (JL): The 3.6L Pentastar engine received a significant update starting in 2016 models (like the Grand Cherokee) and was used in the JL Wrangler from 2018. This 'upgraded' version features a two-stage variable valve lift (VVL) system, a higher compression ratio (11.3:1 vs 10.2:1), cooled EGR, and redesigned fuel injectors and ignition coils. While the rocker arm issue can still occur, these changes mean some diagnostic steps or parts may differ between a 2016-2018 JK and a 2018-2023 JL with the same engine.