P0304 on 2015-2016 Dodge Dart: Cylinder 4 Misfire Causes and Fixes

What's Unique About the 2015-2016 Dodge DART

The Dodge Dart was available with three different four-cylinder engines. While standard ignition issues are common across all, the 2.4L Tigershark and 1.4L Turbo engines use Fiat's MultiAir technology. This system, which uses engine oil pressure to control intake valves, is highly sensitive to oil level and quality; low or incorrect oil can cause misfires. A very frequent problem on the 2.4L engine is a leaking valve cover gasket, which allows oil to pool in the spark plug tubes, fouling the spark plug and ignition coil. The 1.4L Turbo engine is particularly sensitive to spark plug wear and requires a strict 30,000-mile replacement interval to prevent misfires.

Diagnostic Flowchart

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

Symptoms You May Notice

• Rough running engine or rough idle. [⭐ TSB #08-027-20]
• Flashing or solid Check Engine Light
• Noticeable loss of power and acceleration
• Engine shaking or stumbling
• Difficulty driving uphill
• Poor fuel economy
• Unpleasant or fuel-like smell from the exhaust

Most Likely Causes

1. Faulty Ignition Coil 🔴 High Probability → Shop Ignition Coil Coil-on-plug systems are a common failure point due to constant heat cycles. On the 2.4L engine, failure is often accelerated by oil leaking from the valve cover gasket, which saturates the coil boot and causes it to fail.
   How to confirm: Swap the ignition coil from cylinder 4 with another cylinder (e.g., cylinder 3). Cylinder 4 is on the driver's side of the engine. Clear the codes and drive the vehicle. If the code changes to P0303, the ignition coil is faulty.
   Typical fix: Replace the failed ignition coil. It is often recommended to replace all coils and spark plugs at the same time for preventative maintenance, especially on higher mileage vehicles.
   Est. part cost: $30-$75 per coil
2. Worn or Fouled Spark Plug 🔴 High Probability → Shop Spark Plug A very common issue on Dart engines is a leaking valve cover gasket that allows oil to seep into the spark plug tubes, fouling the plugs and causing misfires. The 1.4L Turbo engine is very sensitive to plug wear and requires replacement every 30,000 miles. Using plugs with an incorrect gap can also cause misfires.
   How to confirm: Remove the ignition coil and inspect the spark plug well for oil. Remove the spark plug and check for wear (worn electrode), carbon buildup, or oil fouling. The correct gap for the 1.4L Turbo is ~0.028", while the 2.0L/2.4L is ~0.043"-0.047".
   Typical fix: Replace the spark plug. If oil was present, the valve cover gasket and spark plug tube seals must also be replaced. It's best practice to replace all spark plugs as a set.
   Est. part cost: $10-$25 per spark plug
3. Leaking Valve Cover Gasket / Spark Plug Tube Seals 🟡 Medium Probability → Shop Engine Valve Cover This is a very common failure on the 2.4L Tigershark engine. The rubber gaskets become hard and brittle over time, losing their seal and allowing engine oil to leak into the spark plug wells, shorting out the ignition coil and spark plug.
   How to confirm: When you remove the ignition coil for cylinder 4, you will see liquid engine oil pooled in the bottom of the tube or coating the coil boot.
   Typical fix: Replace the valve cover gasket and the integrated spark plug tube seals. 🎬 Watch this step-by-step 2.4L valve cover gasket replacement Thoroughly clean all oil from the spark plug tube and ignition coil boot before reassembly. Fel-Pro and Mopar are common replacement brands.
   Est. part cost: $40-$100 for the gasket set
4. Faulty Fuel Injector ⚪ Low Probability → Shop Fuel Injector
   How to confirm: This is more difficult to diagnose. It involves listening for the injector's clicking sound with a mechanic's stethoscope or swapping the injector with another cylinder, which is labor-intensive. An injector can also be tested for resistance with a multimeter.
   Typical fix: Replace the faulty fuel injector. Sometimes cleaning the injector can resolve the issue.
   Est. part cost: $50-$120

Rare But Worth Checking

• Failed MultiAir Actuator (1.4L & 2.4L engines): On engines with MultiAir, a failure in the hydraulic actuator for cylinder 4 can cause a persistent misfire. This is often accompanied by other codes, like P1064 or P106C (Cylinder 4 Oil Supply Solenoid Valve Stuck/Switch Off Time Out Of Range). This is a more complex and expensive repair, often requiring replacement of the entire MultiAir 'brick'. Ensuring the correct spec engine oil is used and levels are full is critical for the health of this component.
• Poor Electrical Connection at PCM: Some owners have reported that simply disconnecting, cleaning, and reconnecting the main engine computer (PCM/ECM) electrical connectors resolved persistent, hard-to-diagnose misfires.
• Low Cylinder Compression: A worst-case scenario involving internal engine damage such as a bad valve, worn piston rings, or a failed head gasket. This should only be investigated after all ignition and fuel-related causes have been ruled out via a compression test.
• Faulty PCV Valve: → Shop PCV Valve A stuck-open PCV (Positive Crankcase Ventilation) valve can create a vacuum leak, altering the air-fuel mixture and leading to misfires. This is an often-overlooked but relatively inexpensive part to replace.

Diagnosis Steps

1. Read the code with an OBD-II scanner to confirm P0304 and check for any other codes, especially P1064/P106C on MultiAir engines.
2. For MultiAir engines (1.4L, 2.4L), immediately check the engine oil level and condition. Low or incorrect oil can cause misfires.
3. Inspect the wiring and connector for the cylinder 4 ignition coil for any obvious damage.
4. Swap the ignition coil from cylinder 4 to cylinder 3. Clear the codes and run the engine. If the code changes to P0303, the coil is bad and needs replacement.
5. If the code remains P0304, remove the coil again and inspect the spark plug well for oil. If oil is present, the valve cover gasket set needs to be replaced.
6. Remove the spark plug from cylinder 4. Inspect it for wear, damage, or fouling. Replace if necessary, ensuring the correct part and gap.
7. If the misfire persists, the issue may be with the fuel injector or, on MultiAir engines, the actuator brick (especially if P1064/P106C is present).
8. As a final step for persistent issues, a mechanical compression test can rule out internal engine problems.

Parts You'll Likely Need

• Ignition Coil (OEM #Mopar 68242286AB (2.4L), Mopar 5149168AI (2.0L), Mopar 68081914AA (1.4L)) — This is one of the most common failure points for a single-cylinder misfire. They are easy to access and test by swapping.
  Trusted brands: Mopar, NGK, Delphi, Denso
  OEM price range: $60-$90
  Aftermarket price range: $30-$75
• Spark Plug (OEM #NGK SIKR9A7 (1.4L Turbo), Champion REC10WMPB4 (2.0L/2.4L OEM)) — Spark plugs are a routine maintenance item and can become worn or fouled by oil from a leaking valve cover gasket, causing a misfire. The 1.4L Turbo requires replacement every 30k miles.
  Trusted brands: NGK, Champion, Denso
  OEM price range: $15-$25
  Aftermarket price range: $10-$20
• Valve Cover Gasket Kit (OEM #Mopar 5047440AC (2.4L)) — Required if oil is found in the spark plug tube, a very common issue on the 2.4L engine. The kit includes the main gasket and the spark plug tube seals.
  Trusted brands: Mopar, Fel-Pro, Mahle
  OEM price range: $70-$120
  Aftermarket price range: $40-$100

Related Codes That Often Appear With This One

• P0300 — If the misfire is intermittent or affects multiple cylinders, a P0300 (Random/Multiple Cylinder Misfire) 🎬 Watch: Common causes for Dodge Dart engine misfire codes code may be stored alongside P0304. [⭐ TSB #08-027-20]
• P1064 / P106C — On MultiAir engines (1.4L, 2.4L), these codes for the 'Cylinder 4 Oil Supply Solenoid Valve' often appear with P0304, strongly pointing to a problem with the MultiAir actuator 'brick'.

Technical Service Bulletins (TSBs) & Recalls

• 08-027-20: Addresses rough running and multiple misfire codes (P0300, P0301, P0302, P0303, P0304) on 2015 models, may require PCM update.
• 18-034-16: PCM software update for 2016 models with 2.4L engine to address various DTCs including those related to the MultiAir system (P106C for cylinder 4) and disable the misfire monitor when other critical faults are present.

Platform-Specific Known Issues

• A known owner complaint on a 2015 Dart with code P0304 noted that the catalytic converter was turning red from overheating, highlighting the danger of driving with a severe misfire. [ ODI #11681316]
• A Technical Service Bulletin (#08-027-20) was issued for 2015 Darts for multiple misfire codes, including P0304, related to a rough running engine condition, which may require a PCM software update. [⭐ TSB #08-027-20]
• TSB 18-034-16 involves a PCM software update for 2016 Darts with the 2.4L engine, which can address various DTCs and improve engine performance.

Mechanic-Grade Diagnostic Values

• Ignition Coil Primary Resistance (2.4L Engine) — expected: 0.56 - 0.68 Ohms. Failure: A reading outside this range indicates a faulty primary winding in the coil.
• Ignition Coil Secondary Resistance (2.4L Engine) — expected: 7.8 - 9.6 kOhms. Failure: A reading outside this range indicates a faulty secondary winding in the coil.
• Fuel Injector Resistance (2.4L Engine) — expected: Approximately 10 - 16 Ohms. Failure: An injector with a resistance reading significantly different from the others, or an open/short circuit, is likely faulty.
• Fuel Pressure (Low-Pressure System) — expected: Recommended pressure is 80 psi (552 kPa).. Failure: Low fuel pressure can cause lean conditions and misfires, though it would typically affect multiple cylinders.

Hidden / Shadow Codes Worth Checking

• Misfire Counters: Dealer-level scan tools like Mopar's wiTECH do not use proprietary codes but provide live data counters for misfires on each cylinder. A technician can watch these counters increment in real-time to confirm the misfire is isolated to cylinder 4, even if it's not frequent enough to immediately set a code. (see via Mopar wiTECH diagnostic tool or other advanced professional scanners with live data capability.)

Scan Tool Commands That Help

• wiTECH (Mopar Dealer Tool): Misfire TLC Relearn / Clear Mis-fire — After replacing a component that caused the misfire, this function can be used to clear learned adaptations and reset the misfire counters, allowing the PCM to re-learn engine operation with the new part.

Wiring & Ground Locations

• Engine Ground Strap — A primary engine-to-chassis ground strap is located under the front driver's side wheel well.. This ground is notorious for corrosion due to its location. A poor ground can cause a weak spark from the ignition coils, leading to a misfire that mimics a bad coil or plug. Cleaning the contact points for this strap is a common, often-overlooked fix for electrical issues, including misfires.
• G102 — Ground attachment point located under the battery tray in the engine compartment.. This is a central grounding point for multiple engine-related components. Corrosion or looseness here can cause a variety of hard-to-diagnose electrical problems, including intermittent misfires.

Real Owner Repair Stories

• Reddit user in r/dodgedart (2015 Dodge Dart SXT 2.4L) — Check engine light with a cylinder 4 misfire code (P0304) after replacing the alternator and getting an oil change.
  ❌ Tried (didn't work) The user was in the process of diagnosis.
  ✅ What actually fixed it Another user in the thread strongly suggested the cause was a corroded ground strap located under the front driver's side wheel well, noting it's a notorious issue on Darts for causing electrical resistance and various problems.
• Reddit user in r/dodgedart (related engine) (Dodge Dart with 1.4L MultiAir Turbo) — Stumbling during driving, completely dead cylinder at times, rough running.
  ❌ Tried (didn't work) Initial diagnosis focused on common ignition and fuel system parts.
  ✅ What actually fixed it The code was P1067 (Cylinder 2 actuator valve failure). The final fix was replacing the entire MultiAir actuator 'brick'. This highlights a critical failure mode for MultiAir engines that can present as a simple misfire.

"I Checked Everything" — The Actual Cause

• A common scenario for the Dodge Dart is for a technician to perform a smoke test to find a vacuum leak causing a misfire, only to find no leaks. The actual cause in many of these cases has been a poor electrical ground, specifically the engine-to-chassis ground strap under the driver's side wheel well. This corroded connection can cause a weak spark, leading to a misfire that standard fuel and air diagnostic procedures will not uncover.

OEM Part Supersession History

• 68080580AB, 68242286AA → 68242286AB — Part revision and improvement by the manufacturer.
  Heads up: The newest part number, 68242286AB, is the correct service replacement for the 2.4L engine in this vehicle.

Model Year Variations Within This Range

• 2015-2016: While mechanically very similar regarding this fault, the 2016 model year saw minor cosmetic changes and package adjustments, such as a new Sport Appearance Package for the SXT and standard 18-inch Hyper Black wheels on the GT. These changes do not affect the diagnosis or common causes of a P0304 code.