P0303 on 2015-2016 Dodge DART: Cylinder 3 Misfire Causes and Fixes

What's Unique About the 2015-2016 Dodge DART

The Dodge Dart was available with several engines, including the 2.0L, 2.4L MultiAir, and 1.4L Turbo. While P0303 points to a standard ignition problem, the 2.4L 'Tigershark' engine in particular is known for specific issues that lead to misfires. These engines can suffer from excessive oil consumption, and a very common failure is a leaking valve cover gasket that allows oil to pool in the spark plug tubes, fouling the plugs and ignition coils. The plastic clips on the ignition coil connectors are also known to become brittle and break, causing a poor connection and leading to intermittent 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, especially at idle. [Bulletin #08-027-20]
• Flashing or solid Check Engine Light.
• Vehicle jerking or hesitating during acceleration.
• Reduced engine power.
🎬 Watch: A breakdown of common causes for the P0303 code.
• Poor fuel economy.
• Fuel smell from the exhaust.

Most Likely Causes

1. Faulty Ignition Coil 🔴 High Probability → Shop Ignition Coil Heat and vibration in the engine bay can cause ignition coils to fail over time. Numerous owner accounts and mechanic videos point to ignition coils as a frequent cause of misfires on the Dart.
   How to confirm: The easiest way to confirm a bad coil is to swap the ignition coil from cylinder 3 with another cylinder (e.g., cylinder 2). Clear the codes and drive the vehicle. If the code changes to P0302, the coil is faulty.
   Typical fix: Replace the faulty ignition coil. It is often recommended to replace all spark plugs at the same time.
   Est. part cost: $30-$70 per coil
2. Worn or Fouled Spark Plug 🔴 High Probability → Shop Spark Plug Spark plugs are a regular maintenance item. On 2.4L engines, oil leaking from the valve cover gasket is a very common cause of spark plug fouling, leading to a misfire.
   How to confirm: Remove the spark plug from cylinder 3 and inspect it. Look for heavy carbon buildup, oil contamination, or a worn electrode. Compare it to a plug from a different cylinder.
   Typical fix: Replace the spark plugs. For the 2.4L engine, the recommended spark plug gap is 0.047 inches (1.2mm). If oil is present in the spark plug tube, the valve cover gasket and spark plug tube seals must also be replaced.
   Est. part cost: $20-$50 for a set of four spark plugs
3. Leaking Valve Cover Gasket / Spark Plug Tube Seals 🟡 Medium Probability → Shop Engine Valve Cover The gaskets on the 2.4L MultiAir engine are known to become hard and brittle, allowing engine oil to leak directly into the spark plug wells. This is a widely documented issue on the Dart and its platform mates.
   How to confirm: When you remove the ignition coil from cylinder 3, look for liquid engine oil in the bottom of the tube or coating the coil boot and spark plug. 🎬 Watch: How oil in the spark plug tubes causes misfires.
   Typical fix: Replace the valve cover gasket and the integrated spark plug tube seals. 🎬 See this step-by-step 2.4L valve cover gasket replacement guide. It is critical to clean all oil out of the spark plug tube before installing the new spark plug.
   Est. part cost: $40-$80 for the gasket set
4. Faulty Fuel Injector ⚪ Low Probability → Shop Fuel Injector
   How to confirm: After ruling out ignition issues, you can test the fuel injector. One method is to listen for a consistent clicking sound from the injector with a mechanic's stethoscope. Another is to swap the injector with another cylinder and see if the misfire code follows.
   Typical fix: Replace the faulty fuel injector.
   Est. part cost: $50-$120 per injector

Rare But Worth Checking

• Broken Ignition Coil Connector Clip: → Shop Ignition Coil The plastic locking tabs on the ignition coil wiring harness connectors are known to become brittle and break, leading to a loose connection that can cause an intermittent misfire. Carefully inspect the connector for damage when diagnosing.
• Low Engine Compression: Internal engine problems like a leaking valve or worn piston rings can cause a loss of compression, leading to a misfire. This is less common but should be investigated if ignition and fuel system checks pass. A compression test is needed to confirm.
• MultiAir Brick Issues (2.4L and 1.4L Engines): The MultiAir system uses electronically controlled hydraulic solenoids to actuate the intake valves. A failure in the solenoid for cylinder 3 can cause a misfire. This system is highly sensitive to oil level and quality; using oil other than the specified 0W-20 synthetic can lead to problems.
• Faulty PCV Valve: → Shop PCV Valve A stuck-open Positive Crankcase Ventilation (PCV) valve can create a vacuum leak, altering the air-fuel mixture and potentially causing single or multiple cylinder misfires. This is an often-overlooked but simple-to-replace part.

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner to confirm P0303 and any other related codes.
2. Inspect the ignition coil and spark plug for cylinder 3. On the transverse-mounted 4-cylinder Dart engines, the cylinders are numbered 1-2-3-4 from the passenger side (belt side) to the driver side. Cylinder 3 is the third from the passenger side.
3. Check for oil in the spark plug tube. If oil is present, the valve cover gasket and tube seals need replacement.
4. Swap the ignition coil from cylinder 3 with cylinder 2. Clear the codes and run the engine. If the code changes to P0302, the ignition coil is bad and needs to be replaced.
5. If the code remains P0303, swap the spark plug from cylinder 3 with cylinder 1. If the code changes to P0301, the spark plug is faulty. Ensure new plugs for the 2.4L engine are gapped to 0.047 inches.
6. If the misfire persists on cylinder 3, inspect the ignition coil electrical connector for damage or a broken locking tab.
7. If ignition components are good, the next step is to check the fuel injector on cylinder 3. Listen for a steady clicking sound. You can also swap it with another cylinder to see if the fault moves.
8. If all else fails, perform an engine compression test to check for mechanical issues within cylinder 3. Low compression could point to internal engine or MultiAir system problems.

Parts You'll Likely Need

• Ignition Coil (2.4L & 2.0L) (OEM #68242286AB) — This is one of the most common failure points for a single-cylinder misfire on the Dodge Dart.
  Trusted brands: Mopar, NGK, Denso
  OEM price range: $50-$90
  Aftermarket price range: $30-$70
• Spark Plugs (2.4L & 2.0L) (OEM #SP149125AE (Mopar Iridium)) — Worn or fouled spark plugs are a primary cause of misfires and are a standard maintenance item that should be replaced when servicing a misfire. NGK and Champion are common OEM suppliers.
  Trusted brands: Mopar, NGK, Champion
  OEM price range: $40-$60 (set of 4)
  Aftermarket price range: $20-$50 (set of 4)
• Valve Cover Gasket with Spark Plug Tube Seals (2.4L) (OEM #5047440AC) — Required if oil is found in the spark plug wells, a common issue on the 2.4L engine leading to misfires.
  Trusted brands: Mopar, Fel-Pro, Mahle
  OEM price range: $60-$100
  Aftermarket price range: $40-$80

Related Codes That Often Appear With This One

• P0300 — This is a code for 'Random/Multiple Cylinder Misfire'. It can appear alongside P0303 if the misfire is intermittent or starting to affect other cylinders.
• P0301, P0302, P0304 — These codes indicate misfires in cylinders 1, 2, and 4, respectively. If you see these with P0303, it points to a problem affecting the whole engine, like a vacuum leak, low fuel pressure, or issues with the MultiAir system. [Bulletin #08-027-20]
• P0353 — This code stands for 'Ignition Coil C Primary/Secondary Circuit Malfunction'. It specifically points to an electrical problem with the ignition coil or its circuit for cylinder 3, and often appears with P0303 when the coil is the root cause.

Technical Service Bulletins (TSBs) & Recalls

• 08-027-20

Platform-Specific Known Issues

• The 2.4L MultiAir engine has a known issue with excessive oil consumption, which can contribute to fouling spark plugs and other engine problems. This has been the subject of class-action lawsuits.
• Oil leaking from the valve cover gasket into the spark plug tubes is a frequent and well-documented cause of misfires on this platform.
• The plastic connectors for the ignition coils can become brittle and fail to lock securely, causing a poor electrical connection and intermittent misfires.

Mechanic-Grade Diagnostic Values

• Fuel Injector Resistance (2.4L) — expected: Approximately 12 ohms. Failure: A reading significantly different from other injectors, or an open/short circuit.
• Ignition Coil Primary Resistance — expected: 0.4 to 2.0 ohms. Failure: A reading outside of the specified range.
• Ignition Coil Secondary Resistance — expected: 6,000 to 10,000 ohms. Failure: A reading outside of this range indicates a faulty secondary winding.
• MultiAir Solenoid Coil Resistance (2.4L) — expected: 0.2 to 1.0 ohms. Failure: An open circuit (infinite resistance) or a reading outside this very low range indicates a failed solenoid within the MultiAir 'brick'.
• Engine Compression (2.4L) — expected: Approximately 150 PSI per cylinder. Failure: Significantly lower compression in cylinder 3 compared to others.

Scan Tool Commands That Help

• wiTECH (or equivalent professional scanner): Misfire Counter — To monitor live misfire events on each cylinder. This is useful for confirming the misfire is isolated to cylinder 3 and to verify if a repair was successful.
• wiTECH (or equivalent professional scanner): VVT Solenoid Active Test — If a MultiAir system fault is suspected, this command can be used to individually activate the oil control solenoid for each cylinder to check for a response. A lack of response from the cylinder 3 solenoid points to a faulty 'brick'.

Wiring & Ground Locations

• Engine to Chassis Ground — A ground strap runs from the passenger side of the engine's cylinder head to the passenger side strut tower.. Corrosion or a loose connection at this primary ground point is a known issue and can cause a wide range of electrical problems, including erratic sensor readings and misfires.
• Battery to Chassis Ground — The negative battery cable grounds to the chassis in the driver's side fender well area.. A corroded ground at this location can cause numerous electrical issues, including no-start conditions and module communication problems that could potentially be misinterpreted.
• G102 Ground — Located at the left rear corner of the engine compartment.. This is a major grounding point for various engine components. A wiring diagram shows its importance in the overall ground distribution circuit.

Real Owner Repair Stories

• Reddit user on r/dodgedart (2016 Dodge Dart) — Persistent P0303 error code, very sulfurous exhaust smell, distinct tapping from the valve train.
  ❌ Tried (didn't work) Replaced all 4 ignition coils, Replaced all 4 spark plugs, Replaced all 4 fuel injectors, Performed a PCM/ECM hard reset, Replaced the EGR valve
  ✅ What actually fixed it The user suspected a bad lifter or valve, indicating a deeper mechanical engine issue beyond the common ignition and fuel component failures. The final resolution was not posted, but the extensive list of failed fixes points away from common causes and towards internal engine damage.

OEM Part Supersession History

• 68080580AB → 68242286AA, then 68242286AB — Standard part revision and improvement by the manufacturer.
  Heads up: The newer part numbers are direct replacements for the older ones.