P0301 on 2019-2025 Ram 1500: Cylinder 1 Misfire Causes and Fixes

What's Unique About the 2019-2025 Ram 1500

For the 2019-2025 Ram 1500, P0301 can be a simple fix or a sign of deeper engine-specific issues. On the 5.7L Hemi, a persistent P0301 accompanied by a ticking noise can be an early warning of the infamous 'Hemi tick,' which points to potential camshaft and lifter failure related to the Multi-Displacement System (MDS). TSB #18-002-25 directly links P0301 with other MDS-related fault codes like P3400 (Cylinder Deactivation System). For the 3.6L Pentastar, while ignition components are common causes, worn rocker arm bearings are a known issue that can lead to misfires, often after ruling out simpler causes. Several Technical Service Bulletins (TSBs), including #18-031-25 REV. C and #18-021-26, specifically mention P0301 occurring during cold starts, which may be resolved by a PCM software update rather than a mechanical repair.

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 shaky idle.
• Hesitation or stumbling during acceleration.
• Flashing or solid Check Engine Light.
• Noticeable loss of power.
• Decreased fuel economy.
• Smell of unburnt fuel from the exhaust.
• Remote start may be disabled.
• Ticking noise from engine, especially on cold starts (can indicate exhaust manifold leak or lifter issue).

Most Likely Causes

1. Worn or Fouled Spark Plug 🔴 High Probability → Shop Spark Plug The 5.7L Hemi uses two spark plugs per cylinder, increasing the chance of a failure. Standard wear and tear is the primary reason. Extended oil change intervals can also contribute to fouling.
   How to confirm: Remove the spark plug(s) from cylinder 1 and inspect for wear, carbon buildup, oil fouling, or a cracked insulator. An excessively large spark plug gap can also be the cause. Oil in the spark plug tube points to a leaking valve cover gasket.
   Typical fix: Replace the spark plug(s) for cylinder 1. It is highly recommended to replace all spark plugs at the same time for even performance. 🎬 See the full process for changing 5.7L Hemi spark plugs.
   Est. part cost: $15-$25 per plug
2. Faulty Ignition Coil 🔴 High Probability → Shop Ignition Coil
   How to confirm: Swap the ignition coil from cylinder 1 with another cylinder (e.g., cylinder 3). Clear the codes and run the engine. If the code changes to P0303, the coil is bad. Also inspect the coil boot for cracks or signs of moisture intrusion, which can cause a short.
   Typical fix: Replace the faulty ignition coil. It is a simple bolt-on part located on top of the valve cover.
   Est. part cost: $40-$100
3. Failed Camshaft Lobe / Lifter (5.7L Hemi) 🟡 Medium Probability → Shop Engine Camshaft The 5.7L Hemi engine is known for potential camshaft and lifter failure, often attributed to the Multi-Displacement System (MDS) lifters where the roller bearing seizes and grinds the cam lobe. This is often preceded by a distinct ticking sound.
   How to confirm: Listen for a loud, rhythmic ticking noise from the engine. A pressure transducer test can reveal a lack of intake valve lift. A compression test may show low compression in cylinder 1. Visual inspection requires removing the valve cover and potentially the cylinder head.
   Typical fix: This is a major repair requiring replacement of the camshaft, all lifters (often with upgraded non-MDS parts), head gaskets, and related components. This is typically a job for a professional.
   Est. part cost: $800-$2000+
4. Clogged or Faulty Fuel Injector ⚪ Low Probability → Shop Fuel Injector
   How to confirm: You can test the injector's resistance with a multimeter or listen for a clicking sound with a mechanic's stethoscope to ensure it's operating. Swapping the injector with another cylinder is another effective diagnostic step, similar to swapping a coil.
   Typical fix: Replace the faulty fuel injector.
   Est. part cost: $50-$150
5. Worn Rocker Arms (3.6L Pentastar) ⚪ Low Probability → Shop Engine Rocker Arm The Pentastar V6 engine has a known issue with rocker arm needle bearings wearing out, causing them to fail and damage the camshaft, leading to a misfire. This is often diagnosed after a compression test shows low readings on the affected cylinder.
   How to confirm: This requires removing the valve cover for visual inspection of the rocker arms and camshaft lobes for wear or breakage. This is often diagnosed after ruling out ignition and fuel issues.
   Typical fix: Replace all rocker arms and potentially lifters on the affected cylinder bank. If the camshaft is damaged, it must also be replaced. 🎬 Watch: How to replace Pentastar rocker arms and fix the tick.
   Est. part cost: $100-$300 for a set of rocker arms

Rare But Worth Checking

• Cracked Exhaust Manifold / Leaking Gasket: A common issue on Hemi engines is for the exhaust manifold bolts to break, causing a gasket leak or for the manifold itself to crack. This creates a ticking noise, especially on cold starts, and can allow oxygen to enter the exhaust stream, confusing the O2 sensor and potentially triggering a misfire code for a nearby cylinder.
• Low Compression (Mechanical Issue): Beyond lifter failure, a misfire can be caused by a bent valve, broken valve spring, worn piston rings, or a leaking head gasket. A compression test is required to diagnose this.
• PCM Software Glitch: Multiple TSBs (e.g., 18-031-25 REV. C) indicate that misfires, including P0301, can be falsely detected during cold starts. The fix is not mechanical but rather a software update for the Powertrain Control Module (PCM) performed by a dealer.

Diagnosis Steps

1. Read the code with an OBD-II scanner and confirm P0301 is present. 🎬 Watch: A complete diagnostic walkthrough for P0301 on the Hemi. Note any other codes and check freeze frame data to see the conditions when the code was set.
2. Identify Cylinder 1. On the 5.7L Hemi, it's the front-most cylinder on the driver's side. On the 3.6L Pentastar, it's the front-most cylinder on the passenger's side.
3. Swap the ignition coil from cylinder 1 with another cylinder (e.g., cylinder 3). Clear the codes and drive the vehicle. If the code changes to P0303, the ignition coil is the problem.
4. If the misfire remains on cylinder 1, inspect the spark plug(s). Look for wear, damage, or fouling. Check the spark plug gap. Replace if necessary.
5. Listen for a distinct ticking noise. A tick that is loud on a cold start and lessens as the engine warms may be an exhaust manifold leak. A persistent, rhythmic tick could indicate a lifter/camshaft issue.
6. If the coil and plug are good, listen for a steady clicking from the fuel injector with a stethoscope. If silent, it may be faulty. Consider swapping the injector if accessible.
7. Perform a compression test on cylinder 1 to check for mechanical engine problems. Low compression points to issues like bad rings, valves, or a failed head gasket.
8. Check for vacuum leaks around the intake manifold gasket for cylinder 1 using a smoke machine or carburetor cleaner.
9. If all else fails, especially on a high-mileage engine, remove the valve cover to visually inspect for a broken valve spring, worn rocker arms (3.6L), or damaged camshaft lobes (5.7L).

Parts You'll Likely Need

• Ignition Coil (OEM #68238603AA) — Ignition coils are a common failure point that directly causes a lack of spark and a misfire. It's a primary wear item.
  Trusted brands: Mopar, NGK, Delphi
  OEM price range: $60-$100
  Aftermarket price range: $40-$75
• Spark Plug (OEM #SP143877AB (5.7L Hemi)) — Spark plugs have a finite lifespan and are the most common reason for a misfire. The electrode wears down, or they become fouled.
  Trusted brands: NGK, Champion
  OEM price range: $15-$25
  Aftermarket price range: $5-$15
• Camshaft and Lifter Kit (5.7L Hemi) — For the notorious 'Hemi tick' that evolves into a misfire, replacing the camshaft and lifters is the required fix. This is a major mechanical failure common to this engine.
  Trusted brands: Mopar, AMS Racing, Texas Speed
  OEM price range: $1200-$1800
  Aftermarket price range: $800-$1500

Related Codes That Often Appear With This One

• P0300 — If the condition causing the misfire in cylinder 1 is also intermittently affecting other cylinders, a P0300 (Random/Multiple Cylinder Misfire) code may also be stored. This is common with fuel delivery issues or major mechanical problems.
• P030x — If you see other cylinder-specific codes like P0302, P0303, etc., it may point to a systemic issue like bad fuel, a vacuum leak affecting multiple cylinders, or a failing fuel pump.
• P3400, P3401, etc. — On the 5.7L Hemi, P0301 may be accompanied by cylinder deactivation codes (P34xx series), strongly suggesting the misfire is related to the MDS system and potential lifter failure, as noted in TSB #18-002-25.

Technical Service Bulletins (TSBs) & Recalls

• Bulletin #18-031-25 REV. C: Addresses P0301 and other misfire codes set during cold start catalyst heating, recommending a PCM software update.
• Bulletin #18-021-26: Also relates to P0301 and other misfires during cold starts, pointing towards a software fix.
• Bulletin #18-002-25: Links P0301 and other misfire codes directly with cylinder deactivation system (MDS) codes on the 5.7L Hemi, suggesting a PCM reprogram.
• Bulletin #09-011-25: General bulletin for MIL illumination that lists P0301 among many other potential misfire codes.
• Bulletin #18-046-24: Another PCM update bulletin for the 5.7L Hemi that includes P0301 as a covered code.
• Bulletin #08-031-25 REV. B: Pertains to the 3.0L Hurricane engine, but shows a pattern of using software updates to address misfire detection, including P0301.

Platform-Specific Known Issues

• 5.7L Hemi Lifter Failure: A P0301 code, especially when paired with a ticking noise, is a well-documented symptom of camshaft and lifter failure in Hemi engines equipped with MDS. This is a significant and costly repair. TSB #18-002-25 confirms the link between misfire codes and cylinder deactivation system codes.
• Cold Start Misfires (Software Issue): TSB #18-031-25 REV. C and others note that P0301 can be set during cold start catalyst heating. This may not be a mechanical fault; a dealer can perform a PCM software update to correct the sensitive misfire detection logic.
• 3.6L Pentastar Rocker Arm Failure: While less common than on older Pentastar versions, the 3.6L can suffer from rocker arm bearing failure, leading to a tick and eventual misfire. One owner on RamForum.com with a 2020 3.6L chased a P0301 after swapping plugs and coils, with a potential head/valvetrain issue being the next diagnostic step.
• Cracked Exhaust Manifolds (5.7L Hemi): The Hemi is also prone to cracked exhaust manifolds or broken manifold bolts, causing a leak. This is often misdiagnosed as the 'Hemi tick' from the valvetrain. An owner on 5thGenRams.com reported a cracked manifold on a 2019 with only 26k miles. While it may not always set a misfire code, the resulting change in O2 sensor readings can contribute to it.

Mechanic-Grade Diagnostic Values

• Fuel Pressure (Key On, Engine Off) — expected: 58 PSI +/- 5 PSI. Failure: Pressure below 53 PSI indicates a weak fuel pump or leak. Pressure that bleeds down quickly after the pump primes indicates a faulty check valve in the pump assembly.
• Ignition Coil Primary Resistance — expected: ~0.5 - 0.8 Ohms. Failure: A reading of OL (over-limit/infinite) or significantly outside this range indicates a failed coil winding.
• Cranking Compression — expected: ~170-180 PSI. Failure: Significantly lower pressure indicates a mechanical issue like a worn piston ring, leaking valve, or bad head gasket. Unusually high pressure (e.g., 280 PSI) can indicate excessive carbon buildup or an issue with valve timing.

Scan Tool Commands That Help

• wiTECH or equivalent professional scan tool: Cylinder Power Balance Test — This is a primary diagnostic step to confirm which cylinder is misfiring without swapping parts. The tool deactivates each cylinder one by one and measures the RPM drop. A cylinder that causes little to no RPM drop when deactivated is not contributing power and is the source of the misfire.
• wiTECH or equivalent professional scan tool: Misfire Counter (Live Data) — While driving under the conditions noted in the freeze frame data, monitoring the live misfire count for each cylinder can confirm the fault is on cylinder 1 and see if other cylinders are misfiring intermittently, even if not enough to set their own codes.

Wiring & Ground Locations

• Cylinder 1 Ignition Coil Control Wire — At the ignition coil connector for cylinder 1 (front-most cylinder on the driver's side for 5.7L Hemi).. The wire from the PCM that commands the coil to fire is a Black wire with a Gray tracer (BK/GY). Checking for a pulsed ground signal on this wire with a noid light or scope can determine if the PCM is correctly commanding the coil to fire, helping to isolate a wiring/PCM issue from a bad coil.
• Engine Ground Strap(s) — Key grounds are located from the battery to the chassis sidewall, from the chassis to the engine block (often near the alternator on the passenger side), and at the back of the cylinder head(s) to the firewall or bell housing.. A poor engine ground can cause a weak spark, erratic sensor readings, and misfires that are difficult to diagnose. A loose or corroded ground on the bell housing, in particular, can cause a host of issues that may mimic fuel or ignition component failure.
• ECM Ground Strap (68603896AA) — This specific strap provides a ground path for the Engine Control Module (ECM/PCM).. A compromised ground specifically for the ECM can cause it to misinterpret sensor data or send weak/erratic signals to the ignition coils and fuel injectors, leading to a misfire code.

Real Owner Repair Stories

• YouTube Video 'Code PO301 - Cylinder Misfire | How to Diagnose & Fix | Ram Truck Hemi 5.7L' (4th Gen Ram 1500 5.7L Hemi (procedure applicable to 5th Gen)) — P0301 misfire code immediately after the engine was pressure washed.
  ❌ Tried (didn't work) Initial diagnosis pointed towards common coil/plug failure.
  ✅ What actually fixed it Upon removing the cylinder 1 ignition coil, the technician found significant moisture inside the spark plug boots. The fix was to thoroughly dry the coil, boots, and spark plug wells with compressed air and apply dielectric grease before reassembly. The code was cleared and did not return.
• Ram Forum thread 'Cylinder #1 misfire (P0301) and CEL, but only at 4500/5000 rpm and above' (2016 Ram 1500 5.7L Hemi) — Flashing check engine light and P0301 code specifically when the engine RPM exceeded 4500, such as when downshifting or climbing a grade. Drove normally at lower RPMs.
  ❌ Tried (didn't work) Driving gently to keep RPMs low.
  ✅ What actually fixed it A mechanic replaced all spark plugs and ignition coils. After the replacement, the truck ran fine and the high-RPM misfire was resolved. This suggests a weak ignition component was failing only under high load/high RPM conditions.
• Reddit thread r/ram_trucks 'Po301 error.' (2010 Ram 1500) — Solid check engine light with P0301 code. No immediate drivability issues or loud ticking.
  ❌ Tried (didn't work) The code cleared itself temporarily but returned.
  ✅ What actually fixed it The owner replaced the spark plugs, and the problem was solved.

OEM Part Supersession History

• 56029129AF, 68060346AA → 68238603AA — Part revision and consolidation by the manufacturer.
• 68366240AD → 68603896AA — Part revision for the ECM ground strap.

Model Year Variations Within This Range

• 2019-2025: The 5.7L Hemi engine was available with or without the eTorque mild-hybrid system. The eTorque system adds a 48-volt belt-starter generator. While no specific P0301 causes are unique to eTorque, its presence adds complexity to the electrical and charging system diagnostics. TSBs #18-031-25 REV. A and #18-031-25 specifically mention software updates for cold start misfires related to fuel pump actuation, which may be more prevalent on newer models within this range.
• 2019-2025: The 'Ram 1500 Classic' sold during these years is a continuation of the 4th generation (DS) platform and has different body styling and some different interior features, but shares the core 3.6L and 5.7L powertrains and their associated issues.