P0308 on 2014 Chrysler 300: Cylinder 8 Misfire Causes and Fixes

What's Unique About the 2014-2014 Chrysler 300

For the V8-equipped Chrysler 300, a P0308 code must be diagnosed with an awareness of the HEMI engine's specific weaknesses. While common ignition or fuel issues are often the cause, these engines have a well-documented history of lifter failure. The needle bearings inside a lifter can fail, causing the roller to seize and subsequently grind down the corresponding camshaft lobe, leading to a persistent misfire on that cylinder. This issue is often accompanied by a distinct ticking sound, commonly referred to as the 'Hemi tick', which may be more noticeable on cold starts or at idle. The Multi-Displacement System (MDS), which deactivates cylinders to save fuel, uses specialized lifters that are a common point of failure.

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 vibrating idle
• Hesitation or stumbling during acceleration
• Noticeable loss of engine power
• Check engine light is on and may be flashing
• Increased fuel consumption
• Audible ticking or tapping noise from the engine (if related to lifter failure), often described as a light, rhythmic tap from the top of the engine.
• Smell of unburned fuel from the exhaust

Most Likely Causes

1. Faulty Ignition Coil 🔴 High Probability → Shop Ignition Coil Ignition coils are a common wear-and-tear component on most modern engines, responsible for generating the spark for the spark plugs. The high heat in the HEMI engine bay can degrade the coil's internal windings and epoxy over time, leading to a weaker spark.
   How to confirm: Swap the ignition coil from cylinder 8 with another cylinder (e.g., cylinder 6 on the same bank). Clear the codes and drive the vehicle. If the code changes to P0306, the ignition coil is faulty.
   Typical fix: Replace the faulty ignition coil. It is often recommended to replace all coils on higher mileage vehicles, but it's not required.
   Est. part cost: $40-$100
2. Worn or Fouled Spark Plugs 🔴 High Probability → Shop Spark Plug The 5.7L HEMI engine uses two spark plugs per cylinder (16 total), increasing the statistical chance of a single plug failing. Spark plugs are a routine maintenance item with a recommended change interval. Oil leaking from a valve cover gasket can also foul the plugs.
   How to confirm: After ruling out the coil, remove the spark plugs from cylinder 8 and inspect them for wear, carbon buildup, oil fouling, or damage. Compare them to a new plug. The recommended gap for the 2014 🎬 See this walkthrough on replacing Hemi spark plugs and coils. 5.7L HEMI is typically 0.044 inches.
   Typical fix: Replace the spark plugs for cylinder 8. It is best practice to replace all 16 spark plugs at the same time to ensure even performance and avoid future misfires.
   Est. part cost: $80-$200 for a full set of 16 plugs
3. Failed Camshaft Lobe and Lifter 🟡 Medium Probability → Shop Engine Camshaft A known weakness in some HEMI V8 engines involves the lifter's roller needle bearings failing, often due to lubrication issues or design. This causes the lifter to seize and destroy the camshaft lobe, preventing the valves for that cylinder from opening and closing correctly. This is often preceded by a ticking noise that can be intermittent at first. 🎬 Watch: Learn why Hemi lifters fail and how to prevent it.
   How to confirm: This is typically diagnosed after ignition and fuel issues are ruled out. A persistent ticking noise from the engine is a strong indicator. A mechanic can perform a compression test on cylinder 8; low compression would point towards a mechanical issue. Visual inspection requires removing the valve cover to check for lack of movement or a dislodged rocker arm for cylinder 8.
   Typical fix: This is a major and expensive repair that involves replacing the camshaft, all lifters (many owners opt for a non-MDS conversion kit), head gaskets, and related components. It is often recommended to replace the oil pump at the same time.
   Est. part cost: $500-$2000+
4. Faulty Fuel Injector ⚪ Low Probability → Shop Fuel Injector
   How to confirm: After ruling out ignition components, the fuel injector can be tested. A mechanic can check the injector's electrical circuit or swap the injector with one from another cylinder to see if the misfire code moves.
   Typical fix: Replace the faulty fuel injector for cylinder 8.
   Est. part cost: $70-$150

Rare But Worth Checking

• Wiring Harness Issue: An open or short in the wiring to the ignition coil or fuel injector for cylinder 8 can mimic a failed component. This should be checked before replacing more expensive parts. Rodent damage to wiring is also a possibility.
• Low Compression (Other Causes): While often related to cam/lifter failure on this engine, low compression can also be caused by a bad valve, a broken valve spring, worn piston rings, or a failed head gasket, though these are less common for a single-cylinder misfire.
• Leaking Valve Cover Gasket: → Shop Engine Valve Cover A failed valve cover gasket can allow oil to seep into the spark plug tubes, fouling the spark plugs and causing a misfire. If you find oil on the spark plug boot when removing it, this is the likely cause.

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner and confirm P0308 is present. Note any other codes, especially P0300.
2. Listen for a distinct ticking or tapping noise from the engine, especially the passenger side valve cover area. A tick strongly suggests a mechanical valvetrain issue.
3. Swap the ignition coil from cylinder 8 (passenger side, rearmost) with cylinder 6 (passenger side, second from rear). Clear the codes and drive. If the code changes to P0306, the coil is bad.
4. If the misfire remains on cylinder 8, inspect the two spark plugs from cylinder 8. Check for heavy wear, fouling, or oil in the spark plug tube. Replace if necessary. It's best practice to replace all 16.
5. If the misfire remains, inspect the wiring and connector for the ignition coil and fuel injector for any visible damage, corrosion, or loose connections.
6. If wiring appears okay, test the fuel injector. This can be done by swapping it with another cylinder's injector or by having a professional test its function and flow.
7. If all ignition and fuel components for cylinder 8 test good, a mechanical issue is likely. Perform a compression test on cylinder 8. Low compression indicates a problem like a failed camshaft/lifter, bad valve, or piston rings.
8. For suspected lifter failure, a technician can remove the passenger side valve cover and, while the engine is running, observe the rocker arms for cylinder 8 to see if they are moving significantly less than the others. A dislodged rocker arm is a definitive sign of a collapsed lifter.

Parts You'll Likely Need

• Ignition Coil (OEM #68238603AA) — This is one of the most common failure points for a single-cylinder misfire. It's a high-wear item responsible for generating the spark. This part number supersedes 56029129AA, 56029129AB, 56029129AF, and 68060346AA.
  Trusted brands: Mopar, NGK, Duralast
  OEM price range: $90-$140
  Aftermarket price range: $40-$80
• Spark Plugs (Set of 16 for 5.7L) (OEM #SP143877AB) — Spark plugs are a routine maintenance item and a primary cause of misfires as they wear out. The 5.7L HEMI requires 16 plugs. This part number supersedes 68143877AB and SP143877AA.
  Trusted brands: NGK, Champion, Denso
  OEM price range: $150-$220
  Aftermarket price range: $80-$160
• Camshaft and Lifter Kit (OEM #53022263AF (Camshaft), 53021720AE (Lifters)) — In the case of the 'Hemi tick' and confirmed mechanical failure, a full kit is needed to replace the worn camshaft and the failed lifters that caused the damage. Many owners opt for a non-MDS lifter kit to prevent future failures.
  Trusted brands: Mopar, Melling, Enginetech
  OEM price range: $1000-$1800
  Aftermarket price range: $500-$1200

Related Codes That Often Appear With This One

• P0300 — If the misfire becomes more widespread or is intermittent across multiple cylinders, a P0300 (Random/Multiple Cylinder Misfire) code may appear alongside P0308. This is common when lifter failure begins.
• P0335 — As noted in TSB #18-094-16, a Crankshaft Position Sensor code can sometimes appear with misfire codes, as the PCM relies on this sensor to detect misfires.

Technical Service Bulletins (TSBs) & Recalls

• 18-094-16: Lists P0308 - Cylinder 8 Misfire among other potential diagnostic trouble codes that may be addressed by a PCM software update.

Platform-Specific Known Issues

• TSB #18-094-16 mentions P0308 in a list of potential

Mechanic-Grade Diagnostic Values

• Ignition Coil Primary Resistance — expected: Approximately 0.55 - 0.61 Ohms. Failure: A reading significantly higher or lower than the expected range, or an open circuit (OL).
• Fuel Injector Resistance — expected: Approximately 11.4 - 12.6 Ohms at 68°F (20°C). Failure: A reading outside of this range, or a reading that is more than 0.5-1.0 Ohm different from the other injectors.
• Fuel Pressure (at fuel rail) — expected: Approximately 48-54 PSI. Failure: Pressure that is significantly lower than specification can cause lean misfires across multiple cylinders, but could present on one first.
• Engine Compression (per cylinder) — expected: 120-150 PSI, with less than 10-15% variation between cylinders.. Failure: A reading on cylinder 8 that is significantly lower than the other cylinders points to a mechanical issue like a bad valve, worn rings, or cam/lifter failure.

Hidden / Shadow Codes Worth Checking

• Mode $06, TID $A9-$B0, CID $01-$08: Mode $06 data on a generic OBD-II scanner can display misfire counts for each cylinder for the current and last 10 driving cycles. Cylinders are identified by Component ID (CID), e.g., CID $08 for cylinder 8. This allows a technician to see if misfires are occurring even if they aren't frequent enough to set a P0308 code yet. (see via An OBD-II scan tool with Mode $06 functionality.)

Scan Tool Commands That Help

• wiTECH (Chrysler Dealer Tool) or equivalent high-level scanner: Cylinder Kill / Injector Kill Test — This bidirectional command allows a technician to manually disable the fuel injector for cylinder 8. If the engine's idle quality does not change when cylinder 8 is disabled, it confirms that cylinder is not contributing, verifying the misfire location.
• wiTECH or equivalent: View Misfire Counters — Live data PIDs for misfire counts (e.g., 'Misfire Counter Cyl 8') provide a real-time count of misfire events. This is more immediate than Mode $06 and is crucial for confirming if a repair has been successful during a test drive.

Wiring & Ground Locations

• Cylinder 8 Ignition Coil Connector — Passenger side of the engine, rearmost coil.. The PCM sends the signal to fire the coil through this connector. A damaged connector or wire here will cause a P0308. The control wire is typically a Dark Green/Tan wire leading to pin 35 on the C2 PCM connector.
• Cylinder 8 Fuel Injector Connector — Passenger side of the engine, under the fuel rail, rearmost injector.. The PCM controls the fuel injector through this connector. A wiring fault will prevent fuel from being delivered, causing a misfire. The control wire is typically a Dark Green/Gray wire leading to pin 34 on the C2 PCM connector.
• G901A / G902A — Front of the engine compartment, often on the frame rails or shock towers.. These are primary engine compartment grounds. A loose or corroded ground at these points can cause numerous electrical issues, including weak spark or erratic sensor readings that could lead to a misfire code.
• Engine Block to Chassis Ground — A braided strap typically running from the back of the engine block to the firewall/body.. This is the main ground path for the engine block and all components attached to it, including the alternator and cylinder heads. A poor connection here can cause intermittent and hard-to-diagnose electrical problems, including misfires.

Real Owner Repair Stories

• YouTube user comment on a P0308 diagnostic video (2002 Dodge Ram 1500 w/ 225k miles (similar HEMI architecture)) — Check engine light, ticking noise, loss of power, P0308 code.
  ❌ Tried (didn't work) Shop quoted $8500 for a new engine., Friends suggested long block replacement.
  ✅ What actually fixed it The owner removed the valve cover and found the rocker arm for cylinder 8 had completely fallen off due to a collapsed lifter. He replaced the single failed lifter and the rocker arm for a total cost of $115, which resolved the P0308 code and restored engine power.

Model Year Variations Within This Range

• 2014: The 2014 model year is a single year, so there are no significant mid-year changes affecting this specific trouble code. The vehicle is part of the second generation (LD) which began in 2011.