P0308 on 2011-2023 Dodge Charger HEMI: Cylinder 8 Misfire Causes and Fixes

What's Unique About the 2011-2023 Dodge Charger

While ignition component failure is common on any vehicle, the HEMI V8 platform has a well-documented history of camshaft and lifter failures. This issue, often starting as a ticking noise, can manifest as a single-cylinder misfire like P0308. This is particularly prevalent on the 5.7L engine's Multi-Displacement System (MDS) lifters but can occur on all HEMI variants. The MDS lifters can fail, causing the roller to seize and grind down the camshaft lobe, which prevents the valve from opening correctly and results in a persistent misfire. Therefore, a persistent P0308 code that isn't resolved by new plugs or coils warrants a more serious mechanical inspection.

Symptoms You May Notice

• Rough or shaky idle
• Hesitation or stumbling during acceleration
• Noticeable loss of engine power
• Flashing or solid Check Engine Light
• Smell of unburnt fuel from the exhaust
• Audible ticking or tapping sound from the engine bay, often called the 'Hemi Tick'

Most Likely Causes

1. Faulty Ignition Coil 🔴 High Probability Coil-on-plug systems are a common failure point on modern engines due to constant heat cycles and vibration. Cylinder 8 is at the rear of the engine bay, which can sometimes experience higher temperatures, potentially accelerating failure.
   How to confirm: Swap the ignition coil from cylinder 8 with another cylinder (e.g., cylinder 6, which is the next one forward on the passenger side). Clear the codes and drive. If the code changes to P0306, the ignition coil is bad.
   Typical fix: Replace the faulty ignition coil. It's often recommended to replace the corresponding spark plug at the same time. Many owners choose to replace all 8 coils preventatively on higher mileage vehicles.
   Est. part cost: $30-$90
2. Worn or Fouled Spark Plug(s) 🔴 High Probability HEMI engines use two spark plugs per cylinder (16 total), increasing the chance of a failure. They are a standard maintenance item and a very common cause for misfires. The recommended service interval should be followed closely.
   How to confirm: After ruling out the coil, remove the two spark plugs from cylinder 8. Inspect them for wear on the electrode, an incorrect gap, carbon buildup, or oil/fuel fouling. A cracked porcelain insulator can also cause a misfire.
   Typical fix: Replace the spark plugs for cylinder 8. It is best practice to replace all 16 spark plugs 🎬 Watch: Step-by-step guide to changing 5.7L HEMI spark plugs. if they are near the end of their service life to ensure even performance.
   Est. part cost: $5-$25 per plug
3. Failed Lifter and/or Worn Camshaft Lobe 🟡 Medium Probability This is a widely known issue on HEMI engines, often called the 'Hemi tick'. The needle bearings in the roller lifters (especially MDS lifters) can fail, causing the roller to seize and grind down the corresponding lobe on the camshaft. This leads to a loss of valve lift and a persistent misfire. A YouTube video by a Ram 1500 owner shows a P0308 caused by a rocker arm that had completely fallen off due to a collapsed lifter.
   How to confirm: If ignition and fuel system checks do not resolve the misfire, and a ticking noise is present, a mechanical inspection is required. This involves a compression test on cylinder 8. A low reading points towards a mechanical issue. Visual inspection requires removing the passenger-side valve cover to check for dislodged rocker arms or lack of movement, which are 🎬 Watch: How to diagnose the cause of HEMI tick. clear signs of a collapsed lifter.
   Typical fix: This is a major engine repair that involves replacing the camshaft, all 16 lifters, head gaskets, and related components. Many owners opt for an MDS-delete kit at this time to prevent future failures. A user on a Ram forum mentioned being quoted $9,550 for a cam replacement, highlighting the significant cost.
   Est. part cost: $800-$2000+
4. Faulty Fuel Injector ⚪ Low Probability
   How to confirm: Listen to the injector with a mechanic's stethoscope to hear if it's clicking steadily. You can also perform a resistance test with a multimeter or swap the injector with another cylinder to see if the misfire code follows (this is more labor-intensive).
   Typical fix: Replace the faulty fuel injector and its seals.
   Est. part cost: $50-$150

Rare But Worth Checking

• Vacuum Leak: A vacuum leak near the intake manifold runner for cylinder 8 could lean out the mixture and cause a misfire, but it would typically affect adjacent cylinders as well or throw a lean code (P0171/P0174).
• PCM or Wiring Issue: While very rare, a damaged wire in the harness leading to the coil or injector for cylinder 8, or an internal failure of the PCM driver for that cylinder, can cause P0308. Some TSBs address misfire codes via a PCM software update.
• Rodent Damage: A user on a Reddit forum reported that a P0308 code on their Ram was ultimately caused by a rodent chewing through an injector wire, which can be difficult to spot.

Diagnosis Steps

1. Use an OBD-II scanner to confirm P0308 is the only code present. Note if the check engine light is solid or flashing. Check engine oil level and condition, as low or dirty oil can contribute to lifter problems.
2. Locate cylinder 8. On all Dodge HEMI V8s, it is the rearmost cylinder on the passenger's side of the engine bay, closest to the firewall. The passenger side bank is numbered 2-4-6-8 from front to back.
3. Swap the ignition coil from cylinder 8 with the coil from cylinder 6 (the cylinder directly in front of it). Clear the codes and run the engine to see if the misfire moves. If you now have a P0306 code, the ignition coil is the problem.
4. If the code remains P0308, inspect the spark plug tube for any oil, which would indicate a leaking valve cover gasket seal. Then, replace the two spark plugs for cylinder 8. Check the old plugs for signs of damage, heavy carbon deposits, or oil fouling.
5. If the misfire persists, check the fuel injector. Listen for a steady clicking sound with a mechanic's stethoscope. For a more definitive test, the injector can be swapped with another cylinder, but this is more labor-intensive.
6. If ignition and fuel components have been ruled out, listen carefully for the 'Hemi tick'. Perform a compression test on cylinder 8. A significantly lower reading compared to other cylinders points to a mechanical problem.
7. If a mechanical issue is suspected, remove the passenger-side valve cover and inspect the valvetrain for cylinder 8. Look for a loose or dislodged rocker arm, which is a definitive sign of a collapsed lifter and likely camshaft damage.

Parts You'll Likely Need

• Ignition Coil (OEM #68238603AA (replaces 56029129AF, 68060346AA)) — This is one of the most common failure items for a single-cylinder misfire. It's responsible for generating the high voltage for the spark plugs.
  Trusted brands: Mopar, NGK, Delphi, Bosch
  OEM price range: $50-$100
  Aftermarket price range: $30-$75
• Spark Plug (OEM #SP143877AB (5.7L), SP149212AC (6.4L), SP196724AC (6.2L)) — Spark plugs are a routine maintenance item and a primary cause of misfires as they wear out. HEMI engines use two per cylinder.
  Trusted brands: NGK, Champion
  OEM price range: $10-$25
  Aftermarket price range: $5-$20
• Camshaft and Lifter Kit (OEM #53022263AF (Camshaft, 5.7L), 5038785AD (MDS Lifters)) — Required if the misfire is caused by the common HEMI lifter/cam failure. This is a major mechanical issue. Kits often include the camshaft, 16 lifters, gaskets, and bolts.
  Trusted brands: Mopar, Melling, Comp Cams, AMS Racing
  OEM price range: $1000-$1800
  Aftermarket price range: $800-$1500

Related Codes That Often Appear With This One

• P0300 — If the misfire is intermittent or beginning to affect other cylinders due to a systemic issue like a failing camshaft or fuel delivery problem, a P0300 (Random/Multiple Cylinder Misfire) code may appear alongside P0308.
• P0335 — Manufacturer Bulletin #18-094-16 notes that a P0308 misfire may be accompanied by codes for the Crankshaft Position Sensor Circuit.
• P0122 / P0123 — TSB #18-094-16 also indicates that Throttle Position Sensor circuit codes may appear in conjunction with cylinder misfires.

Technical Service Bulletins (TSBs) & Recalls

• TSB #18-006-24: For some 2023+ models, this TSB notes that various misfire codes, including P0308, may be resolved by reprogramming the PCM with updated software to correct overly sensitive misfire detection.
• Bulletin #1400322REVA: This manufacturer bulletin documents that customers may describe a rough idle or misfire while driving associated with P0308.
• Bulletin #18-094-16: This TSB lists P0308 as a potential diagnostic trouble code that may be present alongside sensor circuit issues in the power train.
• A general TSB for Audi (01-13-67) shows the principle that sometimes misfire codes that don't resolve with plug/coil replacement can be due to ECM software needing an update, a logic that can apply to other manufacturers.

Platform-Specific Known Issues

• The 'HEMI Tick': A ticking or tapping sound from the engine, especially when warm at idle, is a common symptom of a failing lifter. This can eventually lead to a P0308 code as the valvetrain degrades.

Mechanic-Grade Diagnostic Values

• Ignition Coil Primary Resistance — expected: 0.4 to 0.6 ohms. Failure: A reading outside this range indicates a faulty coil winding.
• Ignition Coil Secondary Resistance — expected: 5,000 to 7,200 ohms (5.0-7.2 kOhms). Failure: A reading outside this range indicates a faulty secondary winding.
• Fuel Injector Resistance (High Impedance) — expected: 12 to 17 ohms. Failure: A reading significantly outside this range, or a large deviation from the other injectors, points to a bad injector coil.
• Fuel Pressure (Key On, Engine Off) — expected: Approximately 48-55 PSI. Failure: Low fuel pressure could indicate a weak fuel pump, causing a lean condition and misfires, though it would likely affect multiple cylinders.
• Engine Compression — expected: 120 to 150 PSI, with all cylinders within 10% of each other.. Failure: A reading on cylinder 8 that is significantly lower than the others indicates a mechanical issue like a worn piston ring, bad valve, or failed head gasket.

Hidden / Shadow Codes Worth Checking

• Mode 6, Test ID $A2-$A9: This is not a shadow code, but a data stream within any advanced OBD-II scanner. Test IDs $A2 through $A9 correspond to misfire counts for cylinders 1 through 8, respectively. For P0308, a technician would monitor Test ID $A9. (see via Access Mode 6 data on an OBD-II scan tool. The value for Test ID $A9 will show the raw misfire count for cylinder 8, even before it's high enough to trigger a CEL.)

Scan Tool Commands That Help

• Chrysler wiTECH: Cylinder Cutout / Power Balance Test — This bidirectional function allows a technician to manually deactivate individual cylinders one by one. When cylinder 8 is deactivated, if there is no change in engine RPM or sound, it confirms that cylinder 8 was not contributing in the first place, pinpointing the misfire without swapping parts.
• Chrysler wiTECH: PCM Reprogram/Flash — Several Technical Service Bulletins (TSBs) exist for HEMI platforms that address misfire codes (including P0300-series) by updating the PCM software. If diagnosis reveals no component faults, checking for an available PCM update is a critical step.

Wiring & Ground Locations

• Cylinder 8 Ignition Coil Connector — Rearmost connector on the passenger side valve cover.. The connector has two pins. One should have battery voltage with the key on (KOEO), and the other is a pulsed ground signal from the PCM. Verifying voltage and signal confirms the wiring and PCM driver are functional.
• Main Engine Ground — A key ground strap is located on the passenger side of the engine bay, under the air intake box, attaching the engine to the chassis. Another is on the driver's side cylinder head.. A loose or corroded main engine ground can cause erratic electrical behavior for all components, including the ignition coils and injectors, leading to intermittent and hard-to-diagnose misfires.

Real Owner Repair Stories

• YouTube channel 'Ram 1500 P0308 and Tick' (2006 Ram 1500 (similar HEMI architecture)) — P0308 code, audible engine tick.
  ❌ Tried (didn't work) Replacing the spark plug on cylinder 8., Swapping ignition coils between cylinders.
  ✅ What actually fixed it Upon removing the valve cover, the owner discovered the rocker arm for one of the valves on cylinder 8 had completely fallen off and was lying in the head. This was caused by a collapsed lifter, which is a classic HEMI failure mode. The fix required replacing the lifters and reinstalling the valvetrain.
• YouTube channel 'Auto Repair Champs' (2014 Ram 2500 Heavy Duty 5.7L HEMI) — P0300 and P0308 codes.
  ❌ Tried (didn't work) Initial diagnosis pointed towards common issues.
  ✅ What actually fixed it A compression test showed only 25 PSI on cylinder 8. After removing the valve cover, the technician found bent pushrods. The video notes that in other cases, this can be caused by a broken valve spring, which is also a known issue on these engines.

OEM Part Supersession History

• 56029129AF → 68238603AA — Supplier change and potential design revision for reliability.
  Heads up: The parts are interchangeable and have the same fit and function. The original part number was also preceded by 56029129AA and 56029129AB.
• 05037479AA / AB / AC → 05037479AD — Minor revisions to the fuel injector over the production run.
  Heads up: All versions are generally interchangeable for the 5.7L HEMI within the specified years. Aftermarket equivalents often list all part numbers as compatible.

Model Year Variations Within This Range

• 2015+: Various TSBs were released for 2015 and newer models involving PCM software updates to address misfire detection logic and other powertrain enhancements. For example, TSB 18-047-16 for the 6.2L and 18-061-17 for other engines involve flashing the PCM to resolve certain DTCs, including P0300-series codes.

Diagnostic Flowchart

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0306 — Cylinder 6 Misfire Detected. This code will appear during diagnosis if you swap a faulty ignition coil from cylinder 8 to cylinder 6 to test it.
• P0300 — Random/Multiple Cylinder Misfire Detected. Often accompanies a specific cylinder misfire if multiple spark plugs are worn or if the engine has widespread lifter issues.
• P0208 — Injector Circuit/Open - Cylinder 8. Related to the fuel injector on cylinder 8, which is one of the potential causes for a P0308 misfire.
• P0358 — Ignition Coil 'H' Primary/Secondary Circuit. Points directly to an electrical issue with the cylinder 8 ignition coil, a primary suspect for P0308.

Frequently Asked Questions