P0303 on 2015-2019 Ram ProMaster City: Cylinder 3 Misfire Causes and Fixes

What's Unique About the 2015-2019 Ram PROMASTER CITY

The 2.4L Tigershark engine in the ProMaster City is known for two specific issues that directly lead to misfire codes like P0303. First, it suffers from excessive oil consumption due to piston ring design, which can foul spark plugs. This is so common that FCA has issued warranty extensions and TSBs like 09-003-23 to address it. Second, the valve cover gasket and its integrated spark plug tube seals frequently fail, allowing oil to leak directly onto the ignition coils and spark plugs, causing them to short out. These two problems make ignition system failures the most common cause of P0303 on this van.

Diagnostic Flowchart

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

Symptoms You May Notice

• Rough, shaky idle
• Engine stumbling or hesitating during acceleration
• Noticeable loss of power
• Flashing or solid Check Engine Light
• Reduced fuel economy
• Engine may be difficult to start
• Smell of gasoline from the exhaust

Most Likely Causes

1. Failed Ignition Coil or Damaged Coil Boot 🔴 High Probability → Shop Ignition Coil Oil leaks from the valve cover gasket are very common, soaking the coil boot and causing the spark to ground out. Heat cycles also degrade the coil itself over time. TSB 08-027-20 was issued specifically to address the coil boots failing and causing misfires.
   How to confirm: Swap the ignition coil from cylinder 3 with another cylinder (e.g., cylinder 2). Clear the codes and drive. If the code changes to P0302, the coil is faulty. 🎬 Watch: How to diagnose misfire codes on the 2.4L engine. Visually inspect the coil boot for swelling, cracks, or a coating of engine oil.
   Typical fix: Replace the faulty ignition coil. It is recommended to replace the spark plug at the same time. If oil was present, the valve cover gasket must also be replaced to prevent repeat failure.
   Est. part cost: $25-$60
2. Worn or Oil-Fouled Spark Plug 🔴 High Probability → Shop Spark Plug The engine's tendency to consume oil can foul the spark plug electrodes, preventing a proper spark. The manufacturer specifies Iridium plugs, which can be damaged if not handled correctly. Oil from a leaking valve cover gasket is also a primary cause of fouling.
   How to confirm: Remove the spark plug from cylinder 3. Inspect for a coating of black, oily residue, or check for a worn electrode or incorrect gap. The correct gap is 0.047 inches (1.2mm).
   Typical fix: Replace the spark plug. It is best practice to replace all four spark plugs at the same time to ensure even performance.
   Est. part cost: $8-$15 per plug
3. Leaking Valve Cover Gasket / Spark Plug Tube Seals 🟡 Medium Probability → Shop Engine Valve Cover The gasket and integrated tube seals are a well-documented failure point on the 2.4L Tigershark engine, leading to oil filling the spark plug wells. This is one of the most common root causes for P030x codes on this platform.
   How to confirm: When you remove the ignition coil for cylinder 3, look for liquid engine oil in the spark plug tube or on the coil boot. The presence of any oil confirms the gasket set has failed.
   Typical fix: Replace the valve cover gasket and the spark plug tube seals (which come as a set). Clean all oil out of the spark plug tube before installing 🎬 Watch: An easy trick to remove oil from spark plug wells. the new plug and coil. New valve cover bolt grommets are also recommended.
   Est. part cost: $25-$50
4. Clogged or Defective Fuel Injector ⚪ Low Probability → Shop Fuel Injector
   How to confirm: Listen to the injector with a mechanic's stethoscope to ensure it's clicking. For a more definitive test, you can swap the injector with another cylinder and see if the misfire code follows. This is more labor-intensive than an ignition coil swap. A noid light can also confirm if the injector is receiving an electrical pulse from the ECU.
   Typical fix: Replace the faulty fuel injector.
   Est. part cost: $40-$90

Rare But Worth Checking

• Low Engine Compression: The 2.4L Tigershark's oil consumption issue is linked to piston ring problems, which can eventually lead to loss of compression. If you've replaced ignition and fuel parts and the misfire persists, a compression test is the next step.
• Failed PCV Valve: → Shop PCV Valve The PCV valve is integrated into the valve cover on this engine. If it fails or clogs, it can cause excessive crankcase pressure, leading to oil leaks (including into the spark plug tubes) and creating a vacuum leak, both of which can cause misfires. Often, the entire valve cover is replaced if the PCV valve is confirmed bad.

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner. Note if the Check Engine Light is solid or flashing. Check for any other codes, especially P106x codes which indicate a MultiAir system fault.
2. Check the engine oil level. An extremely low level points towards the known oil consumption issue and can affect the MultiAir system.
3. Swap the ignition coil from cylinder 3 to cylinder 2. Clear the codes and run the engine. If the code changes to P0302, the ignition coil is bad and needs replacement.
4. If the code remains P0303, remove the ignition coil and spark plug from cylinder 3.
5. Inspect the spark plug well for any signs of liquid oil. If oil is present, the valve cover gasket set must be replaced.
6. Inspect the spark plug for signs of oil fouling, carbon buildup, or electrode wear. Ensure the gap is 0.047 inches (1.2mm). Replace if necessary.
7. Real-World Example: A user on a forum reported P0303 and P0304. After finding oil on the valve cover, they replaced the valve cover gasket set, spark plugs, and tubes. They then swapped coils #3 and #1. The code followed the coil, changing to P0301, confirming the coil was also bad. Replacing the coil resolved the issue.
8. If the coil, plug, and well are all good, the problem may be with the fuel injector or engine mechanicals.
9. Listen to the cylinder 3 fuel injector with a stethoscope; it should have a regular, audible clicking sound. Use a noid light to confirm the injector is receiving a signal from the ECU.
10. If all else fails, perform an engine compression test to check for internal mechanical problems like bad rings or valves.

Parts You'll Likely Need

• Ignition Coil (OEM #68242286AA, 68080580AB) — This is one of the most common failure items for a single-cylinder misfire, especially when exposed to oil from a leaking valve cover gasket.
  Trusted brands: Mopar, Delphi, NGK, Standard Motor Products
  OEM price range: $50-$80
  Aftermarket price range: $25-$50
• Iridium Spark Plug (OEM #NGK LFR5AIX-11 (Stock #4469) or NGK 96355 (Ruthenium)) — Spark plugs are a routine maintenance item and are frequently fouled by the oil consumption issues on this engine. Iridium is the recommended material for longevity and performance.
  Trusted brands: NGK, Champion, Denso
  OEM price range: $15-$25
  Aftermarket price range: $8-$15
• Valve Cover Gasket Set (OEM #5184596AE) — This is the root cause of oil leaking into the spark plug tubes, which is a very common problem on the 2.4L engine leading to misfires. The set includes the main gasket and spark plug tube seals. 🎬 See this walkthrough for replacing the valve cover gasket. [NOTE: See Pass 3 Correction - this P/N may be incorrect for the 2.4L engine].
  Trusted brands: Mopar, Fel-Pro, Mahle
  OEM price range: $40-$60
  Aftermarket price range: $25-$45

Related Codes That Often Appear With This One

• P0300 — If the underlying cause, like a major vacuum leak or severe oil consumption, affects multiple cylinders, a P0300 (Random/Multiple Cylinder Misfire) will be stored alongside P0303.
• P0301, P0302, P0304 — These codes indicate misfires in other cylinders. Seeing them together often points to a systemic issue like fouled plugs from oil consumption or a failing valve cover gasket leaking into multiple wells.

Technical Service Bulletins (TSBs) & Recalls

• 18-068-19: Lists P0303 as a potential Diagnostic Trouble Code.
• 08-027-20: Addresses rough running and misfire codes (including P0303) by replacing all four ignition coil insulating boots. This bulletin confirms a known weakness in the ignition system's seal against the elements and oil.
• 09-003-23 (and previous revisions): Details the procedure for an oil consumption test, which may lead to engine replacement if the vehicle qualifies.

Platform-Specific Known Issues

• Excessive Oil Consumption: The 2.4L Tigershark engine is subject to multiple Technical Service Bulletins (TSBs) and warranty extensions (like XB1) for consuming excessive amounts of oil. This can lead to fouled spark plugs, engine stalling, and catastrophic failure if the oil level is not checked frequently. Owners may be eligible for an oil consumption test and potentially an engine replacement under TSB 09-003-23.
• Ignition Coil Boot Failure: TSB #08-027-20 was released specifically to address misfires by replacing the ignition coil boots and applying special grease, acknowledging a design or material issue with the original boots. This applies to the ProMaster City and its platform mates.

Mechanic-Grade Diagnostic Values

• Ignition Coil Primary Resistance — expected: 0.4 to 2.0 Ohms. Failure: A reading outside this range indicates a faulty primary coil winding.
• Ignition Coil Secondary Resistance — expected: 6,000 to 10,000 Ohms (6-10 kOhms). Failure: A reading outside this range suggests a faulty secondary coil winding.
• Fuel Injector Resistance — expected: Approximately 10 to 16 Ohms. Failure: An injector with a significantly different resistance reading compared to the other cylinders, or an open/short circuit, is likely faulty.
• Low-Side Fuel Pressure (Key On, Engine Off) — expected: 58-64 PSI. Failure: Pressure below this range can indicate a weak fuel pump, causing lean conditions and misfires across multiple cylinders.

Hidden / Shadow Codes Worth Checking

• P1062, P1064, P1067, P106B, etc.: These are manufacturer-specific codes related to the MultiAir (VVA - Variable Valve Actuation) system, often indicating a problem with a specific cylinder's oil supply solenoid valve. For example, P1067 indicates 'Cylinder 2 Oil Supply Solenoid Valve Switch On Time Out of Range'. The presence of these codes alongside a P030x code strongly points to a failure in the MultiAir 'brick' rather than a simple ignition or fuel part failure. (see via Most standard OBD-II scanners should be able to read these P1xxx codes.)

Scan Tool Commands That Help

• wiTECH (FCA Dealer Tool): VVA (MultiAir) Solenoid Actuation Test — Use this bidirectional command to directly test the oil control solenoids on the MultiAir 'brick'. This helps isolate whether a solenoid is failing to respond, which is a critical step before condemning the entire expensive actuator assembly.
• wiTECH (or other advanced scan tool): Cam/Crank Variation Relearn — This procedure is required any time a major powertrain component has been replaced, including the MultiAir valve train assembly. Failure to perform this relearn can cause running issues and potentially new trouble codes.
• wiTECH (FCA Dealer Tool): Misfire TLC Relearn / Clear Mis-fire — This function can be used to reset misfire counters and adaptive learning within the PCM after a repair has been completed to ensure the system is starting from a clean slate.

Wiring & Ground Locations

• Main Engine Ground Strap — Typically a braided metal strap connecting the engine block or transmission case directly to the vehicle chassis or the negative battery terminal.. A poor or corroded main engine ground can cause a host of electrical issues, including weak spark and erratic sensor readings, which can lead to misfire codes. Ensuring this connection is clean and tight is a fundamental diagnostic step.
• Cylinder 3 Ignition Coil Connector — On top of the valve cover, plugged into the ignition coil for the third cylinder from the passenger side.. This 2-pin connector supplies power from the Auto Shutdown (ASD) relay and a trigger signal from the PCM. Damage to these wires or a loose connection will directly cause a misfire on cylinder 3.

Real Owner Repair Stories

• Go-Parts.com repair documentation for Jeep Renegade 2.4L (2015-2021 Jeep Renegade with 2.4L Tigershark engine) — Persistent P0301 misfire, rough idle, and hesitation.
  ❌ Tried (didn't work) Replacing the spark plug for the misfiring cylinder., Replacing the ignition coil for the misfiring cylinder., Swapping coils and plugs with other cylinders (misfire always returned to the original cylinder).
  ✅ What actually fixed it Replacing the valve cover gasket set (Mopar P/N 05047440AC). The original gasket had failed, allowing oil to leak into the spark plug well, which was the root cause of the persistent misfire.

"I Checked Everything" — The Actual Cause

• A technician may perform a smoke test to find a vacuum leak causing a rough idle or misfire codes, and find no leaks. The actual cause may not be air leaking in, but a hydraulic issue within the MultiAir system. Low or dirty engine oil can starve the electro-hydraulic actuators that control the intake valves, causing misfire-like symptoms that a smoke test would never find.

When the Usual Fixes Don't Work

• In cases where swapping the ignition coil and spark plug does not resolve the P0303 code, and the misfire does not move to the other cylinder, the root cause is often not the ignition component itself. A real-world repair story on a platform-mate vehicle showed that even after swapping parts, the misfire remained until the leaking valve cover gasket was replaced, which had been fouling the new parts.

OEM Part Supersession History

• 68242286AA, 68080580AB → 68242286AB — Part revision and consolidation by the manufacturer.

Model Year Variations Within This Range

• 2015-2019: While no major changes occurred within the ProMaster City's 2.4L engine in this range, FCA did issue PCM software updates for the broader platform (e.g., Jeep Cherokee) to alter engine parameters and help mitigate the excessive oil consumption issue. It is possible that later model year vehicles received this updated software from the factory.