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

What's Unique About the 2014-2021 Dodge CHALLENGER

On the Dodge Challenger's Hemi V8 engines, a P0308 code can sometimes point to a more serious issue beyond typical ignition parts. These engines, particularly those with the Multi-Displacement System (MDS), are known for potential lifter and camshaft failures. While cylinder #8 is not an MDS cylinder, it is at the back of the engine's oiling system, making it susceptible to oil starvation issues that can lead to lifter seizure and camshaft damage, causing a persistent misfire.

Diagnostic Flowchart

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

Generation note: The 2014-2021 range covers the third generation of the Dodge Challenger, which received a significant facelift in 2015. However, the underlying V8 engine architectures (5.7L, 6.4L, 6.2L) are similar, making the diagnostic process for a P0308 code consistent across these years.

Symptoms You May Notice

• Rough idle or the engine shaking while stopped.
• Hesitation or jerking during acceleration.
• Noticeable loss of engine power.
• Flashing or solid Check Engine Light.
• A decrease in fuel economy.
• A smell of fuel from the exhaust.
• Audible ticking or tapping noise from the engine (the 'Hemi tick'), which can indicate a failing lifter.

Most Likely Causes

1. Faulty Ignition Coil 🔴 High Probability → Shop Ignition Coil Cylinder 8 is located at the rear of the engine bay, where heat can build up and contribute to premature failure of electronic components like ignition coils.
   How to confirm: Swap the ignition coil from cylinder 8 with another cylinder (e.g., cylinder 6). Clear the codes and drive the vehicle. If the code changes to P0306, the coil is bad.
   Typical fix: Replace the faulty ignition coil. This is a single component that sits on top of the spark plug.
   Est. part cost: $40-$100
2. Worn or Fouled Spark Plugs 🔴 High Probability → Shop Spark Plug Hemi engines use two spark plugs per cylinder. Over time, they wear out and can no longer produce a strong enough spark for complete combustion. The service interval can be missed, leading to misfires.
   How to confirm: Remove and inspect the two spark plugs from cylinder 8. Look for a worn electrode, incorrect gap, heavy carbon deposits, or oil fouling.
   Typical fix: Replace the spark plugs for cylinder 8. It is highly recommended to replace all 16 spark plugs at the same time for even performance. 🎬 Watch: How to remove Hemi coil packs and spark plugs.
   Est. part cost: $8-$20 per plug
3. Defective Fuel Injector 🟡 Medium Probability → Shop Fuel Injector
   How to confirm: Listen to the injector with a mechanic's stethoscope; it should have a consistent clicking sound. You can also swap the injector with another cylinder to see if the misfire code follows it, or measure its resistance with a multimeter.
   Typical fix: Replace the clogged or failed fuel injector for cylinder 8.
   Est. part cost: $70-$150
4. Failed Camshaft Lobe / Seized Lifter ⚪ Low Probability → Shop Engine Camshaft This is a well-documented issue on Hemi engines, often called the 'Hemi tick'. Oil starvation can cause a lifter's roller to seize, which then grinds down and destroys the corresponding lobe on the camshaft.
   How to confirm: This is a mechanical failure. After ruling out ignition and fuel issues, a compression test may show low readings. A definitive check involves removing the valve cover and observing the rocker arms while the engine is cranked; a failed lobe will result in visibly less movement on the affected valve compared to others.
   Typical fix: This is a major engine repair requiring the replacement of the camshaft, all lifters, and associated gaskets and seals. One Ram owner reported a $6,900 repair bill for this job.
   Est. part cost: $800-$2000+

Rare But Worth Checking

• Vacuum Leak: A leak in the intake manifold gasket near cylinder 8 can lean out the air/fuel mixture and cause a misfire. This can be detected with a smoke test.
• Low Engine Compression: Beyond a lifter failure, low compression can be caused by worn piston rings or a poor valve seal, requiring a compression test to diagnose and significant mechanical repair.
• Leaking Valve Cover Gasket: → Shop Engine Valve Cover A failed valve cover gasket can allow engine oil to leak into the spark plug tube for cylinder 8, fouling the spark plug and ignition coil, leading to a misfire.
• Damaged Wiring Harness: The wiring for the ignition coil or fuel injector can be damaged, often by rodents. A visual inspection may reveal chewed or frayed wires.
• Internal PCM Failure: In very rare cases, the internal driver circuit for the cylinder 8 ignition coil within the Powertrain Control Module (PCM) can fail. If all other parts test good, the PCM itself may be the culprit.

Diagnosis Steps

1. Read the code with an OBD-II scanner to confirm P0308 is present.
2. Identify cylinder 8. On Dodge V8s, it is the rear-most cylinder on the driver's side (left bank).
3. Swap the ignition coil from cylinder 8 with cylinder 6 (the cylinder in front of it). Clear the codes and run the engine. If the code changes to P0306, the ignition coil is faulty.
4. If the code remains P0308, inspect the spark plugs for cylinder 8. Replace them if they are worn, fouled, or past their service life. Check for oil in the spark plug tube, which would indicate a leaking valve cover gasket.
5. If the plugs and coil are good, check the fuel injector. Listen for a steady clicking sound. If possible, swap the injector with another cylinder to see if the fault moves.
6. Inspect the wiring harness leading to the cylinder 8 coil and injector for any signs of damage, such as burns or rodent chews.
7. Check for vacuum leaks around the intake manifold near cylinder 8 using a smoke machine or by carefully spraying brake cleaner and listening for a change in engine RPM.
8. If all else fails, perform a compression test on cylinder 8. A significantly lower reading compared to other cylinders points to a mechanical issue.
9. If compression is low, consider removing the driver's side valve cover to visually inspect the rocker arm and valve spring movement for cylinder 8 as the engine is cranked. Lack of movement confirms a wiped camshaft lobe/failed lifter.

Parts You'll Likely Need

• Ignition Coil (OEM #68238603AA) — This is the most common point of failure for a single-cylinder misfire and is a simple part to replace. This part number is applicable to 5.7L, 6.2L, and 6.4L Hemi engines.
  Trusted brands: Mopar, NGK, Denso
  OEM price range: $60-$100
  Aftermarket price range: $40-$75
• Spark Plugs (OEM #SP149212AC (6.4L) / SPLZFR5C11 (5.7L)) — Spark plugs are a routine maintenance item and a frequent cause of misfires as they wear out. Hemi engines have 16 total.
  Trusted brands: NGK, Champion
  OEM price range: $12-$20 per plug
  Aftermarket price range: $8-$15 per plug
• Fuel Injector (OEM #53011614AA (6.2L)) — A clogged or electronically failed injector will prevent fuel from entering the cylinder, causing a misfire. Note that the 6.2L injector is not a direct fit for 5.7L/6.4L engines.
  Trusted brands: Mopar, Bosch
  OEM price range: $100-$180
  Aftermarket price range: $70-$120

Related Codes That Often Appear With This One

• P0300 — If the misfire is intermittent or affects multiple cylinders, a P0300 (Random/Multiple Cylinder Misfire) may be stored alongside P0308.
• P2323 — This code for 'Ignition Coil H Secondary Circuit' can appear with P0308, pointing more directly toward a failure in the ignition coil for cylinder 8.
• P0208 — This code for 'Cylinder 8 Injector Circuit Malfunction' specifically points to an electrical problem with the fuel injector or its wiring for cylinder 8.

Technical Service Bulletins (TSBs) & Recalls

• Bulletin #1400322REVA: Confirms P0308 as 'Cylinder 8 Misfire' and notes symptoms like rough idle or misfire while driving.
• Bulletin #18-094-16: Lists P0308 as 'Cylinder 8 Misfire' among a series of potential diagnostic trouble codes related to PCM software updates, though this TSB is for the 2.0L Dart engine, it shows the format of PCM flash bulletins.

Platform-Specific Known Issues

• A known issue with Hemi engines is lifter failure, which can lead to camshaft damage and cause a persistent misfire. This is often preceded by a 'ticking' noise from the engine. While often associated with MDS cylinders, non-MDS cylinders like #8 can also fail due to their position at the end of the oiling galley.

Mechanic-Grade Diagnostic Values

• Fuel Injector Resistance — expected: Approximately 10.0 to 11.0 Ohms for many common injectors, but can vary. All injectors should be within 0.8 ohms of each other.. Failure: A reading significantly outside the specification (e.g., open circuit/infinite resistance) or a reading that deviates significantly from the other injectors indicates a failed injector coil.
• Fuel Pressure (Key On, Engine Off) — expected: Approximately 58 psi (4 bar).. Failure: Significantly lower pressure indicates a weak fuel pump, clogged filter, or faulty pressure regulator. Higher pressure could indicate a regulator issue.
• Ignition Coil Control Circuit Voltage — expected: The PCM grounds this circuit to fire the coil. Using a multimeter, you would test for continuity to ground on the control wire at the coil connector and the PCM connector.. Failure: An open circuit (no continuity) indicates a broken wire between the PCM and the ignition coil.
• Engine Ground Resistance — expected: Less than 1.0 Ohm between the engine block and the negative battery terminal.. Failure: Higher resistance indicates a poor or corroded ground connection, which can cause erratic behavior in sensors and actuators, including ignition coils.

Hidden / Shadow Codes Worth Checking

• Mode 6 Misfire Counters: Modern OBD-II systems, including those in the Challenger, track misfire events per cylinder even before they are frequent enough to set a P0308 code. A technician can view these raw counts to see if cylinder 8 is misfiring intermittently. (see via A professional scan tool (like the dealer's wiTECH) or an advanced consumer scan tool with Mode 6 capabilities. The data is typically found under a menu like 'OBD II Monitors' or 'Misfire Data'.)

Scan Tool Commands That Help

• wiTECH (Dodge/Chrysler Dealer Tool): View 'Which cylinder is misfiring' Monitor — This function provides a live display of misfire counts for all cylinders. It is invaluable for confirming that cylinder 8 is the source of the misfire and for verifying that a repair (like swapping a coil) has successfully moved or eliminated the misfire.
• wiTECH (Dodge/Chrysler Dealer Tool): Actuate Main/ASD Relay — When diagnosing a no-spark condition, this command forces the Auto Shutdown (ASD) relay on. This allows a technician to safely check for battery voltage at the ignition coil's power supply circuit with a test light, confirming the coil is receiving power.
• wiTECH or advanced bidirectional scanner: Fuel Injector Kill / Cylinder Power Balance Test — This test allows the user to disable one injector at a time. When the injector for a good cylinder is disabled, engine RPM will drop. If disabling the cylinder 8 injector causes little or no change in RPM, it confirms that cylinder 8 was not contributing power, pointing towards a fuel, spark, or compression issue in that cylinder.

Wiring & Ground Locations

• C-Series Connectors — C100 series are in the engine compartment, C200 series are in the instrument panel area, and C300 series are in the body.. Knowing the connector numbering scheme helps locate the correct inline harness connectors when tracing the ignition coil or fuel injector circuits from the PCM to the component, which is essential for finding an open or shorted wire.
• Engine Block Ground Strap — Typically a braided strap connecting the engine block (often near the alternator or on the back of the cylinder head) to the vehicle's chassis/frame.. The ignition coils are grounded through the engine block. A loose, corroded, or broken main engine ground strap can cause a weak or intermittent spark on one or more cylinders, leading to misfires that are difficult to diagnose as the coils themselves may test good.
• Cylinder 8 Ignition Coil Connector — On top of the valve cover, connected to the rearmost ignition coil on the driver's side.. This is the primary point for testing. One pin should have battery voltage with the key on (from the ASD relay), and the other is the control wire that the PCM pulses to ground to fire the coil.

Real Owner Repair Stories

• ChallengerTalk Forum Member (2016 Dodge Challenger Scat Pack (6.4L Hemi), ~50,000 miles) — P0308 code, rough idle, and a distinct ticking noise from the engine bay, especially on the driver's side.
  ❌ Tried (didn't work) Swapped ignition coil from cylinder 8 to cylinder 6 (code did not move)., Replaced all 16 spark plugs., Swapped fuel injector from cylinder 8 to cylinder 6 (code did not move).
  ✅ What actually fixed it The owner took the car to the dealership. The dealership performed a compression test which was slightly low on cylinder 8. Upon removing the valve cover, they found the intake rocker arm for cylinder 8 was not moving correctly. The final diagnosis was a failed lifter which had also damaged the camshaft lobe for cylinder 8. The repair involved replacing the camshaft, all lifters, and associated gaskets.

Model Year Variations Within This Range

• 2019-2021 (5.7L V8): Some 5.7L engines in later model years may use a different fuel injector part number (e.g., 05281568A) which is described as an 8-hole injector. While likely compatible, using the correct OEM part number for the specific VIN is critical as flow rates and spray patterns can differ.