P0308 on 2014-2021 Dodge Charger: Cylinder 8 Misfire Causes and Fixes

What's Unique About the 2014-2021 Dodge CHARGER

For the Dodge Charger's HEMI V8 engines (5.7L, 6.2L, 6.4L), a P0308 code must be taken seriously. While it can be caused by simple ignition or fuel issues, it is also a well-documented symptom of lifter failure. The roller lifters, particularly on cylinders using the Multi-Displacement System (MDS), can seize or fail. This causes the lifter to grind against the camshaft lobe, eventually wearing it down and causing a persistent misfire. This issue, often preceded by a ticking noise known as the 'Hemi tick,' is a known mechanical weak point for this engine family. Cylinder 8's location at the rear of the engine can also make it susceptible to issues like heat buildup or being the last in line for oil pressure.

Diagnostic Flowchart

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

Symptoms You May Notice

• Flashing or solid Check Engine Light
• Rough idle or engine vibration
• Hesitation or jerking during acceleration
• Noticeable loss of engine power
• A smell of fuel from the exhaust
• Engine ticking or knocking noise

Most Likely Causes

1. Faulty Ignition Coil 🔴 High Probability → Shop Ignition Coil Coil-on-plug systems are common failure points due to constant exposure to high heat and vibration. It's a frequent cause for single-cylinder misfires and one of the first things to check.
   How to confirm: Swap the ignition coil from cylinder 8 with another cylinder (e.g., cylinder 6, which is next to it on the passenger side). Clear the codes and drive the car. If the code changes to P0306, the ignition coil is the culprit.
   Typical fix: Replace the faulty ignition coil. It is often recommended to replace them in sets if they are original and high-mileage.
   Est. part cost: $40-$90
2. Worn or Fouled Spark Plug 🔴 High Probability → Shop Spark Plug HEMI engines use 16 spark plugs (two per cylinder), and they are a standard wear item. An old, worn, or oil-fouled plug is a very common reason for a misfire.
   How to confirm: Remove the spark plugs from cylinder 8 and inspect them for wear, carbon buildup, oil fouling, or damage to the electrode. Compare them to a plug from a working cylinder. The gap should be checked against specifications (e.g., ~0.044 inches for the 6.4L).
   Typical fix: Replace the spark plug(s) for cylinder 8. It is best practice to replace all 16 spark plugs as a set 🎬 See this walkthrough on changing Hemi spark plugs and coils. if they are near the end of their service life.
   Est. part cost: $5-$15 per plug
3. Failed Lifter and/or Worn Camshaft Lobe 🟡 Medium Probability → Shop Engine Camshaft HEMI V8 engines with MDS are known for lifter failures. The roller bearing on the lifter can seize, causing the lifter to stop rotating and grind a flat spot on the camshaft lobe. This is often preceded by a distinct ticking sound from the engine bay. Cylinder 8 can be particularly vulnerable due to its position in the engine.
   How to confirm: After ruling out ignition and fuel issues, a compression test is the next step. A significantly low reading on cylinder 8 points to a mechanical problem. For definitive proof, a mechanic must remove the valve cover to inspect valve movement while turning the engine. Reduced lift on cylinder 8's rocker arms confirms a wiped cam lobe.
   Typical fix: This is a major repair requiring replacement of the camshaft, all lifters (many owners opt for a full MDS-delete kit), head gaskets, and associated components.
   Est. part cost: $800-$2000 for a kit
4. Faulty Fuel Injector ⚪ Low Probability → Shop Fuel Injector Fuel injectors can become clogged over time or fail electronically, but it's less common than ignition issues.
   How to confirm: Listen to the injector with a mechanic's stethoscope to ensure it's clicking. You can also check its resistance with a multimeter or swap it with another cylinder's injector to see if the misfire code follows.
   Typical fix: Replace the faulty fuel injector.
   Est. part cost: $50-$120

Rare But Worth Checking

• Low Compression / Mechanical Engine Problem: Beyond the common lifter issue, a misfire can be caused by other mechanical problems like a broken valve spring, bent pushrod, or poor piston ring seal, leading to low compression. A compression test followed by a cylinder leak-down test is required to diagnose this.
• Intake Manifold Gasket Leak: → Shop Engine Intake Manifold A vacuum leak near the intake runner for cylinder 8 can lean out the air/fuel mixture enough to cause a misfire. A smoke test is the most effective way to identify such leaks.
• PCM or Wiring Harness Issue: In rare cases, the issue could be with the Powertrain Control Module (PCM) itself or a damaged wire in the harness leading to the coil or injector for cylinder 8. This is usually diagnosed last after all other possibilities are exhausted.

Diagnosis Steps

1. Confirm the P0308 code with an OBD-II scanner and check for any other codes. Note if the check engine light is solid or flashing.
2. Locate cylinder 8. On Dodge HEMI V8s, it is the rearmost cylinder on the passenger's side (the last one closest to the firewall).
3. Swap the ignition coil from cylinder 8 with cylinder 6 (the one in front of it). Clear the codes and test drive. If the code changes to P0306, the coil is bad.
4. If the misfire remains on cylinder 8, inspect and replace the spark plugs for that cylinder. Check for signs of oil, fuel fouling, or excessive wear.
5. Listen for a distinct ticking noise from the passenger side of the engine. A loud tick accompanying a P0308 is a strong indicator of a potential lifter/camshaft issue.
6. If the issue persists, test the fuel injector. Listen for a steady clicking sound. Check the wiring and consider swapping the injector with another cylinder if accessible.
7. Perform a compression test on cylinder 8. A significantly lower reading (e.g., below 120 PSI or more than 20% lower than other cylinders) indicates a mechanical problem.
8. If a mechanical issue is suspected, the next step is to remove the passenger-side valve cover to visually inspect the valve springs, pushrods, and rocker arms for proper movement and integrity.

Parts You'll Likely Need

• Ignition Coil (OEM #68238603AA) — This is one of the most common failure items for a single-cylinder misfire and is easy to diagnose and replace. This part number is widely used across 5.7L, 6.2L, and 6.4L HEMI engines.
  Trusted brands: Mopar, NGK, Denso
  OEM price range: $60-$100
  Aftermarket price range: $40-$80
• Spark Plug (OEM #SP149212AC (for 6.4L), LZFR5C11G (for 5.7L, verify)) — Spark plugs are a routine maintenance item and a primary cause of misfires. HEMI engines have two per cylinder. SP149212AC is the specified plug for many 6.4L applications.
  Trusted brands: NGK, Champion
  OEM price range: $10-$20 per plug
  Aftermarket price range: $5-$15 per plug
• Camshaft and Lifter Kit (OEM #5038419AB (6.4L Camshaft), 05038785AD (MDS Lifters)) — Required for the well-known 'Hemi tick' repair, which is a significant potential cause of P0308. The camshaft and lifters must be replaced together if a lifter has failed and damaged a cam lobe.
  Trusted brands: Mopar, Melling, Comp Cams
  OEM price range: $1000-$1500
  Aftermarket price range: $700-$1200

Related Codes That Often Appear With This One

• P0300 — If the condition causing the P0308 (like low fuel pressure or a major vacuum leak) begins to affect other cylinders, a P0300 (Random/Multiple Misfire) code may appear as well.
• P0335 — As noted in TSB #18-094-16, a faulty crankshaft position sensor circuit can sometimes be logged along with misfire codes, as the sensor is critical for misfire detection.

Technical Service Bulletins (TSBs) & Recalls

• Bulletin #1400322REVA - Confirms P0308 as 'Cylinder 8 Misfire' and notes associated symptoms like 'Rough idle or misfire while driving.'
• Bulletin #18-094-16 - Lists P0308 'Cylinder 8 Misfire' as a potential fault code alongside other powertrain codes.

Platform-Specific Known Issues

• HEMI Lifter/Camshaft Failure: The most significant vehicle-specific issue for P0308 on a Charger V8 is the potential for a failed roller lifter destroying the camshaft lobe. This is a major mechanical failure often starting as a single-cylinder misfire and a ticking sound. The repair is labor-intensive and costly.
• MDS System Complexity: The Multi-Displacement System (MDS), designed to save fuel by deactivating cylinders, uses specialized lifters that are a known failure point. Many owners who perform a camshaft replacement choose to install a non-MDS conversion kit to prevent future failures.

Mechanic-Grade Diagnostic Values

• Fuel Pressure (Key On, Engine Off) — expected: ~58 psi (4 bar). Failure: Significantly lower pressure indicates a weak fuel pump or faulty regulator.
• Ignition Coil Primary Resistance — expected: Typically very low, around 0.5 to 1.5 Ohms. (Note: Manufacturer specs are best, but this is a general range).. Failure: An open circuit (infinite resistance) or a reading far outside the expected range indicates a failed coil.
• Fuel Injector Resistance — expected: Typically 11-14 Ohms for high-impedance injectors used in these applications.. Failure: A reading significantly outside this range, or an open/short circuit, points to a failed injector coil.

Scan Tool Commands That Help

• Chrysler wiTECH: Cylinder Kill Test — To isolate the misfiring cylinder in real-time. When cylinder 8 is 'killed' via the scan tool, there should be little to no change in engine RPM if it is already not contributing, confirming the misfire on that cylinder.
• Chrysler wiTECH: MDS Solenoid Actuation Test — If an MDS-related lifter issue is suspected, this test can command the MDS solenoids on and off to check for proper electrical response. While it won't diagnose a mechanical lifter failure, a failed solenoid could cause issues on an MDS cylinder.

Wiring & Ground Locations

• Cylinder 8 Ignition Coil Connector — Top of the right (passenger side) cylinder bank, at the rearmost position.. The connector receives a power feed (typically a shared wire color like DK BLU/ORG) and a trigger signal from the PCM (a unique wire color for cylinder 8). Verifying battery voltage on the power wire and checking for a pulsed ground signal on the trigger wire can diagnose wiring or PCM driver issues.
• Main Engine Ground — There are multiple grounds. A key ground point is located on the passenger side underneath the air intake box, attached to the chassis. Another is on the driver's side cylinder head.. A poor engine ground can cause erratic behavior in sensors and actuators, including ignition coils and fuel injectors, potentially leading to misfires. Ensuring these connections are clean and tight is a crucial diagnostic step for unexplained electrical issues.
• PCM Location — On the right (passenger) side of the engine compartment.. In rare cases of a PCM driver failure, knowing the location is necessary for testing the specific driver wire for cylinder 8 back to the PCM connector.

Real Owner Repair Stories

• RamForum.com user (Dodge Ram with 5.7L HEMI (mechanically similar to Charger)) — P0300 and P0308 codes (misfire on cylinder 8).
  ❌ Tried (didn't work) Not specified, but the user immediately suspected a major mechanical issue.
  ✅ What actually fixed it The user implies that the root cause is often camshaft/lifter failure on HEMI engines and suggests using a heavier weight oil (10w30) as a preventative measure against such failures, which are known to cause these specific misfire codes.
• Reddit user in r/Justrolledintotheshop (2012 vehicle with 5.7L HEMI) — P0308 - cylinder #8 misfiring.
  ❌ Tried (didn't work) Not specified, but diagnosis led directly to mechanical failure.
  ✅ What actually fixed it Confirmed worn camshaft lobe and failed lifter on cylinder 8. The post includes a picture comparing the damaged camshaft lobe to a new one. The user noted that the MDS lifters were on national backorder, highlighting the prevalence of the issue.

OEM Part Supersession History

• 56029129AA, 56029129AB, 56029129AF, 68060346AA → 68238603AA — Standard part evolution for improved reliability or manufacturing changes.
  Heads up: The newest part number, 68238603AA, is the correct service replacement for the listed older numbers and should be fully compatible.

Model Year Variations Within This Range

• 2009-Present (within the 2014-2021 range): Starting in 2009, the 5.7L HEMI was updated to the 'Eagle' design, which included Variable Valve Timing (VVT) and different cylinder heads compared to the pre-2009 version. The 6.4L 'Apache' HEMI was introduced in 2011. All engines within the 2014-2021 range are of these later VVT designs, so diagnostics are consistent, but parts are not interchangeable with pre-2009 non-VVT engines.