P0306 on 2011-2014 Dodge Avenger: Cylinder 6 Misfire Causes and Fixes

What's Unique About the 2011-2014 Dodge AVENGER

The 2011-2014 Avenger with the 3.6L Pentastar V6 is subject to a well-documented and critical issue regarding its left-side cylinder head. Early versions of this engine (primarily 2011-2013 models built before mid-2012) were prone to excessive wear on valve guides and seats, specifically affecting cylinders 2, 4, and 6. This problem was so prevalent that Chrysler issued Technical Service Bulletin (TSB) #09-002-14 REV. B and a warranty extension (X56, bulletin D-14-12) to address it, often requiring a full cylinder head replacement. Therefore, a P0306 code on this vehicle warrants a more serious investigation beyond typical tune-up parts.

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
• Hesitation or stumbling during acceleration
• Noticeable loss of engine power
• Flashing or solid Check Engine Light
• Reduced fuel economy
• Ticking noise from the top of the engine

Most Likely Causes

1. Failed Left Cylinder Head 🔴 High Probability Early 3.6L Pentastar engines (2011-2013) had a manufacturing defect with improperly hardened valve guides and seats on the left cylinder head, which houses cylinders 2, 4, and 6. This was addressed by TSB #09-002-14 REV. B.
   How to confirm: A professional should perform a cylinder leak-down test. Leakage of 25% or more on cylinders 2, 4, or 6 confirms the issue per the TSB. Air heard escaping from the exhaust or intake during the test is a strong indicator.
   Typical fix: Replacement of the left cylinder head with the updated part (RL141353AC or newer). This was covered under a 10-year/150,000-mile warranty extension (X56) which has now expired for most vehicles.
   Est. part cost: $800-$1500
2. Faulty Ignition Coil 🟡 Medium Probability Coil-on-plug systems are common failure points on many modern engines. Accessing the coils on the left bank (including cylinder 6) requires removing the upper intake manifold, adding labor.
   How to confirm: Swap the ignition coil from cylinder 6 with another cylinder on the same bank (e.g., cylinder 4). Clear the codes and drive the vehicle. If the code changes to P0304, the coil is bad.
   Typical fix: Replace the faulty ignition coil. The Mopar OEM part number is 5149168AH, which has been superseded by 5149168AI and 5149168AJ.
   Est. part cost: $30-$80
3. Worn Spark Plug 🟡 Medium Probability
   How to confirm: Remove the spark plug from cylinder 6 and inspect it for wear, fouling, or an incorrect gap. Compare it to a new plug. A plug discolored by coolant (e.g., orange) can indicate a more serious head gasket issue.
   Typical fix: Replace the spark plug. It is recommended to replace all six at the same time for even performance. The OEM Mopar/Champion Iridium plug is part number SP149125AE (or superseded SP149125AF). The correct gap is 0.044 inches (1.12 mm). 🎬 Watch: An easy guide to replacing your coils and plugs.
   Est. part cost: $15-$25 per plug
4. Faulty Fuel Injector ⚪ Low Probability
   How to confirm: This is more complex as it also requires removing the intake manifold. A technician can test the injector's resistance with a multimeter; a healthy injector should read between 12 and 16 ohms. A reading significantly higher or lower indicates a bad injector. Swapping injectors is also possible but labor-intensive.
   Typical fix: Replace the faulty fuel injector. It is often recommended to replace all injectors on the same fuel rail at the same time.
   Est. part cost: $50-$150

Rare But Worth Checking

• Rocker Arm/Lifter Failure: The 3.6L Pentastar is also known for a 'Pentastar tick' caused by failing rocker arm bearings. This is a separate issue from the cylinder head defect. A failed rocker arm can destroy the camshaft lobe, leading to a persistent misfire that won't be fixed by plugs or coils. Visual inspection under the valve cover is required.
• Intake Manifold Gasket Leak: A vacuum leak near the intake port for cylinder 6 can lean out the air/fuel mixture and cause a misfire. A smoke test can diagnose this. Since the intake manifold must be removed for many P0306 repairs on this engine, replacing these gaskets is standard practice.

Diagnosis Steps

1. Read the code with an OBD-II scanner to confirm P0306 and check for any other related codes (P0300, P0302, P0304). Note freeze frame data.
2. Locate cylinder 6. On the 3.6L Pentastar in a transverse (FWD) layout like the Avenger, the cylinders are numbered 1-3-5 against the firewall (Bank 1) and 2-4-6 at the front of the vehicle (Bank 2). Cylinder 6 is on the driver's side, closest to the transmission.
3. Since accessing cylinder 6 requires removing the upper intake manifold, a simple coil swap is more involved. If you are performing the labor, it is wise to have a new coil and plug on hand.
4. Once the intake is removed, swap the ignition coil from cylinder 6 with the coil from cylinder 4. Reassemble, clear the codes, and drive. If the code changes to P0304, the ignition coil is faulty.
5. If the misfire remains on cylinder 6, inspect the spark plug. Replace it if it appears worn, damaged, or fouled. It is highly recommended to replace all six plugs at this stage.
6. If the coil and spark plug are good, the next step is to check for the known cylinder head issue, especially on a 2011-2013 model. A cylinder leak-down test is the definitive diagnostic step.
7. If the leak-down test shows leakage over 25% on cylinder 6 (or 2, or 4), the left cylinder head needs to be replaced according to TSB #09-002-14 REV. B.
8. If the leak-down test passes, further diagnostics for a faulty fuel injector (resistance check, swap) or valvetrain issue (visual inspection of rocker arms/camshaft) would be necessary.

Parts You'll Likely Need

• Left Cylinder Head Assembly (OEM #RL141353AC) — This is the official, updated Mopar part to fix the inherent valve guide/seat wear issue on 2011-2013 Pentastar engines that causes P0306.
  Trusted brands: Mopar
  OEM price range: $800-$1500
  Aftermarket price range: $600-$1100
• Ignition Coil (OEM #5149168AH) — A common and simple-to-replace failure item that directly causes a misfire on a single cylinder. The OEM part has been superseded by P/Ns 5149168AI and 5149168AJ.
  Trusted brands: Mopar, NGK, Delphi, MSD
  OEM price range: $50-$80
  Aftermarket price range: $25-$60
• Spark Plug (OEM #SP149125AE) — A standard maintenance item that wears out over time, leading to a weak spark and misfires. The OEM plug is a Champion Iridium plug sold under a Mopar part number.
  Trusted brands: Mopar/Champion, NGK, Autolite
  OEM price range: $15-$25
  Aftermarket price range: $8-$15

Related Codes That Often Appear With This One

• P0300 — If the cylinder head issue is severe, it may cause misfires on other cylinders on the same bank (2, 4), leading to a P0300 (Random/Multiple Misfire) code.
• P0302 — This indicates a misfire on cylinder 2, which is on the same cylinder head (left bank) as cylinder 6 and is also affected by the TSB. Seeing P0302, P0304, and P0306 together is a very strong indicator of the head failure.
• P0304 — This indicates a misfire on cylinder 4, which is on the same cylinder head (left bank) as cylinder 6 and is also affected by the TSB. Seeing these codes together points directly to the known defect.

Technical Service Bulletins (TSBs) & Recalls

• 09-002-14 REV. B: The primary TSB for this issue. It outlines the diagnostic procedure (cylinder leak-down test with a 25% failure threshold) and repair (replace left cylinder head) for P0300, P0302, P0304, or P0306 on affected 2011-2013 models.

Platform-Specific Known Issues

• A known defect in the left cylinder head of 2011-2013 3.6L Pentastar engines can cause excessive valve guide and seat wear, leading to misfires on cylinders 2, 4, and 6.
• Chrysler issued TSB #09-002-14 REV. B and an extended warranty (X56, detailed in bulletin D-14-12) for 10 years or 150,000 miles to cover the cost of diagnosing and replacing the faulty cylinder head. While this warranty has likely expired for all 2011-2014 models, it highlights the prevalence of the issue.

Mechanic-Grade Diagnostic Values

• Fuel Injector Resistance — expected: 12.0 - 16.0 Ohms. Failure: A reading significantly outside this range (e.g., double the resistance or an open/short circuit) points to a failed injector.
• Spark Plug Gap — expected: 0.044 inches (1.12 mm). Failure: An incorrect gap can lead to a weak or inconsistent spark, causing a misfire.
• Mode $06 Misfire Count — expected: Near zero for cylinder 6.. Failure: A high or rapidly increasing count for cylinder 6 in Mode $06 data on an advanced scan tool confirms the PCM is actively detecting misfires on that specific cylinder, even before the CEL flashes.

Scan Tool Commands That Help

• wiTECH (Dealer Tool) or equivalent professional scanner: Cylinder Power Balance Test — This function helps determine the contribution of each cylinder to engine speed. A significant drop-off for cylinder 6 would confirm it is not firing correctly, helping to isolate the issue before physically disassembling parts.
• wiTECH (Dealer Tool) or equivalent professional scanner: Fuel Injector Kill — This bidirectional command allows a technician to disable the fuel injector for cylinder 6. If there is no change in engine idle when the injector is killed, it confirms that the cylinder was not contributing in the first place, pointing to a problem with that cylinder's fuel, spark, or compression.

Wiring & Ground Locations

• G302 — Located at the left kick panel, inside the passenger cabin.. This is a major chassis ground. A loose or corroded connection here can cause a variety of difficult-to-diagnose electrical issues, including erratic sensor readings or weak spark that could contribute to a misfire.
• G301 — Located under the front passenger's seat.. Another key interior ground point. While less likely to directly cause a single cylinder misfire, poor grounding can create electrical noise that affects PCM operation.
• PCM C4 Connector — The largest connector on the Powertrain Control Module (PCM), located in the engine bay.. This connector contains the driver circuits for the ignition coils and fuel injectors. Corrosion or a loose pin for the cylinder 6 coil or injector circuit can directly cause P0306. Wiggling this connector while the engine is running can sometimes reveal a poor connection.

Real Owner Repair Stories

• YouTube user 'Frugal Prepper's Garage & Garden' (2013 Dodge Avenger (engine not specified but symptoms match 3.6L)) — Crank no-start, intermittent misfires, multiple codes. The car would sometimes start but run rough.
  ❌ Tried (didn't work) Re-seating the PCM connector provided a temporary fix, but the problem returned.
  ✅ What actually fixed it The main PCM connector (C2) itself was faulty. Wiggling the connector would induce misfires. The final fix was replacing the connector pigtail, which resolved the intermittent starting and misfire issues.
• Reddit user diagnosing a P0303 on a 2015 Jeep Wrangler 3.6L (2015 Jeep Wrangler 3.6L Pentastar) — P0303 (Cylinder 3 Misfire).
  ❌ Tried (didn't work) Swapped coil pack from cylinder 3 to 5; misfire code did not move., Swapped spark plug from cylinder 3 to another cylinder; misfire code did not move.
  ✅ What actually fixed it An ohms test on the fuel injectors revealed the issue. A good injector read ~12 ohms, while the injector for the misfiring cylinder 3 read 63.2 ohms, indicating it was electrically faulty. Replacing the fuel injector was the correct diagnosis.

OEM Part Supersession History

• RL141353AA, RL141353AB → RL141353AC, which is now replaced by 68141353AC — Supersession to the revised cylinder head design with hardened valve guides and seats to correct the premature wear issue found on 2011-2013 engines.
  Heads up: When replacing the head, a specific Bolt/Plug Kit (Mopar P/N 68154699AA) MUST be used, as the new heads are shipped without oil gallery bolts/plugs. Failure to install this kit will result in trouble codes.

Model Year Variations Within This Range

• 2011-2013 (pre-August 2012 build date): These models are equipped with the original left cylinder head design that is prone to premature valve seat/guide wear, making P0302, P0304, and P0306 highly probable indicators of this specific failure.
• 2014+: Vehicles built from mid-2012 onward, including the 2014 model year, came from the factory with the revised cylinder head, making the head failure a much less likely cause for P0306. For these later years, diagnosis should focus more on standard causes like ignition coils, spark plugs, and injectors.