P0307 on 2015 Ram 2500: Cylinder 7 Misfire Causes and Fixes

What's Unique About the 2015-2015 Ram 2500

This code only applies to the V8 gasoline engines (5.7L & 6.4L HEMI) available in the 2015 Ram 2500, as the 6.7L Cummins is an inline-6 and does not have a seventh cylinder. While ignition components are a common cause of misfires on any vehicle, HEMI engines of this era are notoriously prone to a specific mechanical issue involving the camshaft and lifters. On the 5.7L engine, cylinder 7 is one of the cylinders deactivated by the Multi-Displacement System (MDS), which can contribute to lifter failure. A P0307 code, especially if accompanied by a ticking noise, is often the first symptom of a failing lifter that is beginning to damage the camshaft, a significantly more complex and expensive repair than a simple tune-up.

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
• Engine hesitation or stumbling during acceleration
• Flashing or solid Check Engine Light
• Noticeable loss of engine power
• A ticking or tapping noise from the engine bay, particularly from the driver's side.
• Smell of unburnt fuel or rotten eggs from the exhaust.

Most Likely Causes

1. Faulty Ignition Coil 🔴 High Probability The coil-on-plug design exposes the coils to constant heat and vibration, making them a common failure item on modern engines like the HEMI.
   How to confirm: Swap the ignition coil from cylinder 7 with another cylinder (e.g., cylinder 1). Clear the codes and run the engine. If the misfire code changes to P0301, the ignition coil is faulty. This is the easiest first diagnostic step. 🎬 Watch: How to replace your ignition coils and spark plugs.
   Typical fix: Replace the faulty ignition coil. It is often recommended to replace them all if they are original and the vehicle has high mileage.
   Est. part cost: $30-$80
2. Worn or Fouled Spark Plug 🔴 High Probability HEMI V8 engines use two spark plugs per cylinder (16 total), increasing the chances of a single plug failing or becoming fouled over a long service interval. Oil leaks from the valve cover gasket can also foul the plugs.
   How to confirm: After ruling out the coil, swap the spark plugs from cylinder 7 with another cylinder. If the misfire code moves, the spark plug is the issue. Visually inspect the plug for wear, damage, or fouling (black soot or oil).
   Typical fix: Replace the spark plugs. It is mandatory to replace all 16 spark plugs as a set for even performance. Ensure the correct plug type is used for your specific engine (5.7L vs 6.4L).
   Est. part cost: $50-$150 for a full set
3. Failed Camshaft Lobe and/or Lifter 🟡 Medium Probability The 5.7L and 6.4L HEMI engines are known for issues with the lifter rollers failing, particularly on cylinders with Multi-Displacement System (MDS) like cylinder 7 on the 5.7L. The failed roller grinds down the camshaft lobe, leading to a permanent misfire. This is often preceded by a 'Hemi tick' noise.
   How to confirm: If ignition and fuel system checks do not resolve the misfire, a mechanical issue is likely. A compression test may show lower compression on cylinder 7. The definitive diagnosis requires removing the driver's side valve cover and intake manifold to inspect the lifters and camshaft lobes.
   Typical fix: Requires replacing the camshaft, all 16 lifters (often with an upgraded non-MDS design like 'Hellcat' lifters), head gaskets, and related components. This is a major engine repair. 🎬 Watch this step-by-step guide to replacing Hemi lifters and camshafts.
   Est. part cost: $800-$2000+
4. Faulty Fuel Injector ⚪ Low Probability
   How to confirm: After ruling out ignition components, swap the fuel injector from cylinder 7 with another cylinder. This requires removing the fuel rail. If the misfire code moves to the other cylinder, the injector is bad.
   Typical fix: Replace the faulty fuel injector. Consider replacing all injectors if the vehicle has high mileage or running a strong injector cleaner as a first attempt.
   Est. part cost: $50-$120

Rare But Worth Checking

• Broken Valve Spring: A known, though less frequent, issue on HEMI engines, particularly the 6.4L. A broken spring will cause a loss of compression and a severe misfire. This can be visually confirmed by removing the valve cover.
• Low Cylinder Compression: Beyond a cam/lifter issue, low compression can be caused by a burnt exhaust valve, a bent pushrod, or worn piston rings. A compression test followed by a cylinder leak-down test will diagnose this.
• Wiring Harness Issue: Damage or corrosion to the wiring or connector for the ignition coil or fuel injector on cylinder 7 can interrupt the signal and cause a misfire. A visual inspection and testing for power/ground at the connector is necessary.
• PCM Software Glitch: In some cases, the Powertrain Control Module (PCM) may incorrectly detect a misfire. Chrysler has issued TSBs for other models to update PCM software to correct false misfire detection. Checking for available updates with a dealer is a valid diagnostic step if all else fails.

Diagnosis Steps

1. Use an OBD-II scanner to confirm P0307 is the active code and check for any other codes. Note if the Check Engine Light is solid or flashing.
2. Listen for a rhythmic ticking noise from the driver's side of the engine, which is a strong indicator of a lifter/camshaft issue.
3. Locate cylinder 7, which is the rearmost cylinder on the driver's side of the engine.
4. Swap the ignition coil from cylinder 7 with the coil from cylinder 1 (front driver's side). Clear the codes, run the engine, and rescan. If the code changes to P0301, the coil is bad.
5. If the code remains P0307, swap the two spark plugs from cylinder 7 with those from cylinder 1. If the code moves to P0301, you have a faulty plug. Inspect the old plug for oil or carbon fouling.
6. If the misfire is still on cylinder 7, check the wiring and connector to the coil and fuel injector for any visible damage or corrosion.
7. If wiring is good, the next step is to test the fuel injector. This can be done by swapping it with another cylinder's injector, which requires removing the fuel rail. If the code moves, the injector is faulty.
8. If ignition and fuel components are verified as good, the cause is likely mechanical. Remove the driver's side valve cover to visually inspect for a broken valve spring or bent pushrod.
9. If the valvetrain appears intact, perform a cylinder compression test. A significantly lower reading on cylinder 7 points towards an internal engine problem, very likely the common camshaft/lifter failure.

Parts You'll Likely Need

• Ignition Coil (OEM #68238603AA) — This is one of the most common failure points for a single-cylinder misfire and is the easiest to diagnose by swapping.
  Trusted brands: Mopar, NGK, MSD, Accel
  OEM price range: $40-$100
  Aftermarket price range: $30-$70
• Spark Plugs (OEM #5.7L: SP148183AB (or Champion CY9205); 6.4L: SP143877AB (NGK)) — Spark plugs are a routine maintenance item and can become fouled or worn. HEMI engines have 16 plugs that must be changed as a set. Using the correct type for the engine is critical.
  Trusted brands: Mopar (NGK or Champion), NGK, Champion
  OEM price range: $100-$180 (set of 16)
  Aftermarket price range: $50-$120 (set of 16)
• Camshaft and Lifter Kit — This is the fix for the well-documented HEMI lifter failure. The original lifter fails and destroys the camshaft lobe, so both must be replaced together. Many owners upgrade to non-MDS lifters during this repair.
  Trusted brands: Mopar, Melling, Comp Cams, AMS Racing
  OEM price range: $1000-$2000
  Aftermarket price range: $800-$1500
• Fuel Injector (OEM #5039811AA (6.4L)) — A less common but possible cause of a single-cylinder misfire if it becomes clogged or fails electronically.

Related Codes That Often Appear With This One

• P0300 — If the misfire is severe or intermittent across multiple cylinders, a P0300 (Random/Multiple Cylinder Misfire) may be logged alongside the specific cylinder code. This is common when a camshaft/lifter failure begins or if there is a significant vacuum leak.

Technical Service Bulletins (TSBs) & Recalls

• TSB 09-002-18 REV. A: While for a different model year, this TSB addresses the 'Hemi Tick' and valvetrain noise, instructing technicians to inspect components relevant to lifter and camshaft failures.
• TSB 18-004-18 / 18-006-24: These bulletins involve reprogramming the PCM with updated software to address false misfire detection on other Mopar vehicles. It highlights that software can be a potential cause for misfire codes.
• Bulletin #1810722REVA (2022-06-18): Lists P0307 as 'Cylinder 7 Misfire' among other misfire codes.
• Bulletin #1806216 (2016-06-04): Also lists P0307 as 'Cylinder 7 Misfire'.

Platform-Specific Known Issues

• Camshaft/Lifter Failure: The most significant issue for this platform. The rollers on the hydraulic lifters (especially MDS lifters on the 5.7L) can seize, causing the lifter to grind against the camshaft lobe. This results in a persistent misfire and a ticking sound. If not addressed, metal debris can circulate through the engine, causing catastrophic damage. Using the manufacturer-specified oil viscosity (5W-20 for 5.7L, 0W-40 for 6.4L) and regular oil changes are critical for lifter longevity.
• Broken Valve Springs: While not as common as lifter failure, broken valve springs are a known failure point on HEMI engines, particularly the 6.4L V8. This will cause a sudden, severe misfire and requires removal of the valve cover to diagnose.

Mechanic-Grade Diagnostic Values

• Ignition Coil Primary Resistance — expected: 0.49 - 0.57 Ohms. Failure: A reading outside this range indicates a faulty coil.
• Ignition Coil Secondary Resistance — expected: 9.5 - 11.1 kOhms. Failure: A reading outside this range indicates a faulty coil.
• Fuel Injector Resistance — expected: 10 - 18 Ohms (all injectors should be within 0.5 Ohms of each other). Failure: An injector with a resistance reading significantly different from the others is likely faulty.
• Fuel Pressure (at fuel rail) — expected: Approximately 50-58 psi. Failure: Pressure below 47 psi indicates a problem with the fuel pump or regulator.
• Injector Pulse Width (Live Data) — expected: 2.6 - 3.1 ms at idle. Failure: A significantly higher pulse width on one cylinder (e.g., 6.3 ms) can indicate the PCM is trying to compensate for a clogged injector or other issue.

Hidden / Shadow Codes Worth Checking

• Mode $06, Test ID $A2-$AB: This is not a separate code but a data stream showing raw misfire counts for each cylinder over the current and last 10 driving cycles. It can confirm misfires on cylinder 7 even before they are frequent enough to keep the P0307 code active. (see via Use a professional scan tool (e.g., Autel, Snap-on, wiTECH) with Mode $06 capability. The data is often labeled 'Which cylinder is misfiring' in the OBD II monitors section.)

Scan Tool Commands That Help

• wiTECH (or equivalent professional scanner): Cylinder Power Balance Test — This test systematically disables each cylinder one by one and measures the drop in RPM. A cylinder that causes little or no RPM drop when disabled is not contributing power, confirming the misfire location without swapping parts.
• wiTECH (or equivalent professional scanner): ASD Relay Actuation — Used to verify the power supply circuit to the ignition coils. By commanding the Auto Shutdown (ASD) relay on, you can check for voltage at the coil connector with a test light, ruling out a power-side wiring issue.

Wiring & Ground Locations

• Engine Harness Chafe Point — Inspect the main engine wiring harness where it passes over the front corner of the driver's side cylinder head and near the drive belt idler pulley bracket.. Engine vibration can cause the harness to rub through on sharp metal edges, potentially shorting the wiring for the cylinder 7 ignition coil or fuel injector.
• BCM Harness Chafe Point — In the driver's side footwell, inspect the wiring harness that runs near the manual parking brake pedal mechanism.. Though not directly an engine harness, owners have reported this harness rubbing against the parking brake assembly, causing various electrical issues. While less likely to cause a single cylinder misfire, it's a known chafe point on the vehicle that can lead to unpredictable electrical faults.
• Cylinder 7 Ignition Coil Connector — Rearmost coil on the driver's side of the engine.. This is the connection point for testing the coil control circuit from the PCM. A test light connected here should blink while cranking, confirming the PCM is sending a signal.

Real Owner Repair Stories

• Reddit user on r/ram_trucks (2019 Ram 1500 5.7L with 135k miles) — Flashing check engine light, P0307 and P0300. Live data showed high misfire counts on cylinder 7 and 1, with abnormally high injector pulse width on those cylinders.
  ❌ Tried (didn't work) Swapping ignition coils, Swapping spark plugs
  ✅ What actually fixed it The user removed the fuel rail and injectors for cylinders 1 and 7. Upon flushing them under pressure, black gunk and brown fluid came out. After cleaning and reinstalling the injectors, the truck ran perfectly. The root cause was clogged fuel injectors.
• RamForum.com user (2011 Ram 1500 5.7L HEMI) — P0307, truck runs fine under normal load but misfires with a flashing CEL when accelerating hard or going uphill. A 'Hemi Tick' was audible and strongest near cylinder 7.
  ❌ Tried (didn't work) Changed spark plugs, Changed #7 coil pack, Inspected valve springs (appeared okay), Swapped #1 and #7 fuel injectors (code returned to P0307), Used Seafoam in fuel and oil
  ✅ What actually fixed it The user's detailed report of symptoms, including the ticking noise and misfire under load after trying all common fixes, is a classic description of a camshaft and lifter failure. While the user was still in the diagnostic process, the combination of symptoms points directly to this mechanical failure as the unresolved root cause.

OEM Part Supersession History

• Multiple (53021720AE, etc.) → 5038784AD — This is the part number for the upgraded non-MDS 'Hellcat' lifters. The original MDS lifters are a known failure point.
  Heads up: When replacing factory MDS lifters with these non-MDS lifters (a common and recommended upgrade during a cam/lifter repair), the MDS system must be electronically deactivated in the PCM using a tuner. Failure to do so will result in engine codes and improper operation.
• 68139895AB → 68139895AC — Part revision for the fuel pressure regulator, specifically for the 5.7L V8 CNG engine option.