P0301 on 2015-2020 Ram 2500: Cylinder 1 Misfire Causes and Fixes

What's Unique About the 2015-2020 Ram 2500

For the 2015-2020 Ram 2500, the P0301 code tells two very different stories. On the 6.4L and 5.7L HEMI gas engines, this code can be a simple ignition issue, but it's also a notorious early symptom of a more serious internal problem with the camshaft and lifters. This issue, often called the 'Hemi tick,' occurs when the needle bearings in a lifter's roller fail, causing the roller to seize and grind down the camshaft lobe, preventing proper valve operation. On the 6.7L Cummins diesel, a P0301 is almost always a fuel system problem, typically pointing directly to a faulty fuel injector, which is a common wear item on these high-pressure systems sensitive to fuel quality.

Diagnostic Flowchart

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

Generation note: This year range covers the end of the fourth generation (2015-2018) and the start of the fifth generation (2019-2020) Ram 2500. While the core gasoline (HEMI) and diesel (Cummins) powertrains are similar, some electronics and specific parts may differ. The diagnostic approach for a P0301 code is largely the same across these years. For the 6.7L Cummins, injectors for 2013-2018 pickup models are different from cab & chassis models.

Symptoms You May Notice

• Rough or shaking idle
• Hesitation or stumbling during acceleration
• Noticeable loss of engine power
• Flashing or steady Check Engine Light
• Engine may be hard to start
• Smell of unburnt fuel from the exhaust
• Loud, rhythmic ticking sound from the top of the engine (HEMI engines)

Most Likely Causes

1. Faulty Ignition Coil (HEMI Gas Engines) 🔴 High Probability → Shop Ignition Coil Coil-on-plug systems are exposed to high heat and vibration, leading to eventual failure. Water intrusion from rain or engine washing is a common cause of coil failure.
   How to confirm: Locate cylinder 1 (front-most cylinder on the driver's side). Swap its ignition coil with the coil from another cylinder (e.g., cylinder 3, the second one back on the driver's side). Clear the codes and drive. If the code returns as P0303, the coil is bad. This is the standard first diagnostic step mentioned by owners.
   Typical fix: Replace the faulty ignition coil. It is held on by one small bolt and has one electrical connector.
   Est. part cost: $40-$80
2. Faulty Fuel Injector (6.7L Cummins Diesel) 🔴 High Probability → Shop Fuel Injector The high-pressure common rail fuel system operates at extreme pressures, making injectors susceptible to failure from wear or fuel contamination. Multiple TSBs, including 18-102-22 REV A, link misfire codes to injection system performance issues that may require a PCM software update.
   How to confirm: A professional scan tool is needed to perform a cylinder contribution test (or 'injector kill test'), which can isolate a weak injector. Visual inspection of the wiring harness is also recommended. Many owners on forums confirm that a P0301 code on their Cummins was resolved by replacing the injector.
   Typical fix: Replace the cylinder 1 fuel injector. This is an involved job requiring removal of the valve cover and fuel lines, and may require special tools.
   Est. part cost: $300-$600
3. Worn or Fouled Spark Plugs (HEMI Gas Engines) 🟡 Medium Probability → Shop Spark Plug HEMI engines use two spark plugs per cylinder, and they are a standard maintenance item. Leaking valve cover gaskets can also foul the plugs with oil, causing a misfire.
   How to confirm: After ruling out the ignition coil, remove the two spark plugs from cylinder 1. Inspect them for a worn electrode, heavy carbon buildup, or oil fouling.
   Typical fix: Replace the spark plugs. It is best practice to replace all 16 plugs (2 per cylinder) at the same time for even performance.
   Est. part cost: $8-$20 per plug
4. Failed Lifter and/or Worn Camshaft Lobe (HEMI Gas Engines) 🟡 Medium Probability → Shop Engine Camshaft A well-documented issue known as the 'Hemi tick' involves the roller's needle bearings on the hydraulic lifters failing. This causes the roller to seize, which then grinds down and flattens the corresponding camshaft lobe. This prevents the valve from opening correctly, causing a persistent misfire that will not be fixed by ignition or fuel parts.
   How to confirm: Listen for a loud, rhythmic ticking sound from the engine, especially from the driver's side for cylinder 1. A compression test on cylinder 1 will show lower-than-normal pressure if a valve isn't opening properly. In some cases, the lobe can be wiped without a loud tick. The ultimate confirmation is to remove the valve cover and intake manifold to inspect the lifters and camshaft.
   Typical fix: This is a major repair that involves replacing the camshaft, all 16 lifters, head gaskets, and other related components. It requires significant engine disassembly.
   Est. part cost: $800-$1500 for a cam and lifter kit

Rare But Worth Checking

• Internal ECU/PCM Fault: Several manufacturer TSBs, including #18-107-22 REVA for the 5.7L HEMI and #18-102-22 REV A for the 6.7L Cummins, list various misfire codes (P0300-P0308) as a potential symptom that can be resolved with a PCM software update.
• Low Cylinder Compression (Both Engines): Although less common, a persistent misfire not solved by ignition or fuel parts could be due to mechanical engine wear, such as worn piston rings, a burnt valve, or a leaking head gasket. A broken valve spring is another known, though less common, failure on HEMI engines that can cause this. A compression test is required to diagnose this.

Diagnosis Steps

1. Read the code with an OBD-II scanner and note if the Check Engine Light is steady or flashing. Identify the engine (HEMI gas or Cummins diesel).
2. FOR HEMI: Locate cylinder 1 (front, driver's side). Swap its ignition coil with the coil from cylinder 3 (second one back on the driver's side). Clear codes and drive. If the code returns as P0303, the coil is bad.
3. FOR HEMI: If the code remains P0301, remove and inspect the two spark plugs for cylinder 1. Replace if they are worn, damaged, or fouled with oil/carbon.
4. FOR HEMI: If the issue persists, listen for a loud, rhythmic ticking sound from the engine. This strongly suggests the more serious cam/lifter issue. Perform a compression test on cylinder 1; low compression is a key indicator. If compression is low, the next step is removing the valve cover to visually inspect valve movement.
5. FOR CUMMINS: Diagnosis is more complex. Use a professional-grade scan tool (like AlfaOBD or a Snap-on tool) to perform a cylinder contribution test to confirm if the injector is weak.
6. FOR CUMMINS: Inspect the wiring harness leading to the cylinder 1 injector for any chafing, corrosion, or loose connections.
7. FOR CUMMINS: If the injector cutout test points to cylinder 1, the injector is the most likely cause and should be replaced.
8. FOR ALL: Before replacing expensive components, check with a dealer if any PCM software updates are available, as noted in multiple TSBs.

Parts You'll Likely Need

• Ignition Coil (HEMI Engines) (OEM #68238603AA) — This is the most common failure point for a P0301 on the HEMI V8 engines.
  Trusted brands: Mopar, NGK, Denso
  OEM price range: $60-$90
  Aftermarket price range: $40-$70
• Fuel Injector (Cummins Engine - Pickup) (OEM #68210105AA (Mopar) / 0445120342 (Bosch)) — This is the most common cause for a P0301 on the 6.7L Cummins in a pickup configuration.
  Trusted brands: Bosch (OEM), Mopar, Industrial Injection
  OEM price range: $400-$500
  Aftermarket price range: $300-$450
• Fuel Injector (Cummins Engine - Cab & Chassis) (OEM #525) — Cab & Chassis models use different injectors than pickup models within the same year range.
  Trusted brands: Bosch (OEM), Mopar
  OEM price range: $400-$500
  Aftermarket price range: $300-$450

Related Codes That Often Appear With This One

• P0300 — If the cause of the misfire (like a vacuum leak or major fuel issue) begins to affect other cylinders, a P0300 (Random/Multiple Cylinder Misfire) code may appear alongside P0301.
• P0302, P0303, etc. — If you swap a suspected bad part (like an ignition coil) to another cylinder to test it, the code should follow to that cylinder (e.g., P0301 becomes P0303 after moving the coil to cylinder 3).
• P0607 — As noted in TSBs #18-102-22 REV A and #18-055-22 REV A, this code for 'ECU Internal Performance' can appear with misfire codes on Cummins engines, indicating a potential software issue solvable with a PCM reflash.
• P026B — This code for 'Injection Timing Performance' is listed alongside P0301 in TSB #18-102-22 REV A, strongly suggesting a fuel injector or related fuel system issue on Cummins diesel engines.

Technical Service Bulletins (TSBs) & Recalls

• Applies to 2015 Ram 2500/3500 with 5.7L HEMI engines. Lists P0301-P0308 misfire codes as conditions that may be resolved by a PCM software update. This suggests that before major mechanical diagnosis, checking for an available reflash is a valid step.
• Applies to 2020 Ram 2500/3500 with 6.7L Cummins engines. Lists a wide range of DTCs, including P0301-P0306, that can be addressed with a PCM software update. It also addresses symptoms like idle instability. This bulletin was later superseded by 18-067-23.
• Applies to 2020 Ram Cab Chassis models with the 6.7L Cummins. Also lists P0301-P0306 misfire codes as being potentially fixed by a PCM software update, particularly for vehicles that have had the updated CP3 fuel pump installed under recall Y78.

Platform-Specific Known Issues

• HEMI Cam/Lifter Failure ('Hemi Tick'): On both the 5.7L and 6.4L HEMI engines, a persistent P0301, especially when accompanied by a rhythmic ticking noise, is a strong indicator of a collapsed lifter that has damaged the camshaft. This is a widely known, significant, and costly repair.
• Cummins Injector Sensitivity: The 6.7L Cummins' high-pressure fuel system is extremely sensitive to fuel quality. Contaminated fuel is a leading cause of premature injector failure, which often presents as a single-cylinder misfire code like P0301.

Mechanic-Grade Diagnostic Values

• 5.7L HEMI Ignition Coil Primary Resistance — expected: 0.558 to 0.682 Ω at 77°F (25°C). Failure: A reading outside of this specific range indicates a faulty coil winding.
• General Ignition Coil Secondary Resistance — expected: 6,000 to 10,000 Ω. Failure: A reading significantly outside this range, or an open circuit (OL), points to a failed secondary winding.
• 6.7L Cummins Fuel Injector Resistance — expected: Typically 1.5 to 3.5 Ω. More importantly, all injectors should read within 0.5 Ω of each other.. Failure: A reading of 'OL' (open loop) or 0.0 (short) indicates a dead injector. Any injector with a reading that deviates significantly from the others is suspect.
• Mode 6 Misfire Count per Cylinder — expected: Near zero during normal operation.. Failure: A high or rapidly increasing count for cylinder 1 (Component ID often related to the cylinder number) confirms a misfire is occurring, even if the check engine light isn't on yet.

Hidden / Shadow Codes Worth Checking

• Mode 6, TID:$A2, CID:$01 (example): Mode 6 data allows viewing of raw, non-continuous monitor test results, including misfire counts for each specific cylinder (e.g., Component ID $01 for cylinder 1). This can show which cylinder is misfiring before the count is high enough to set a formal P0301 code and turn on the check engine light. (see via A professional scan tool or advanced OBD-II app that can access Mode 6 test data.)

Scan Tool Commands That Help

• AlfaOBD / Witech / high-end Snap-on: Cylinder Performance Test (or Injector Kill Test) — For Cummins engines, this is the primary diagnostic step. The tool deactivates one injector at a time and measures the drop in RPM. If disabling cylinder 1 causes little or no change in engine speed, it confirms that injector is not contributing power and is likely faulty.
• AlfaOBD: Read Injector IMA/IVA Codes — When replacing a Cummins fuel injector, the new injector's 7-digit calibration code must be programmed into the ECU. If the sticker on the old injector is missing or unreadable, this function can read the currently programmed codes directly from the ECU, which is critical for diagnosis and replacement.
• AlfaOBD / Witech: ASD Relay Actuation Test — For HEMI engines, this command forces the Auto Shutdown (ASD) relay to activate, sending power to the ignition coils and fuel injectors. This allows a technician to test for B+ voltage at the cylinder 1 coil and injector connectors with the engine off, verifying the integrity of the power supply circuit.

Wiring & Ground Locations

• Cylinder 1 Injector Harness (6.7L Cummins) — The main injector harness on the driver's side of the engine splits into two leads. The shorter lead goes to the front set of injectors (1-3).. The wire for cylinder 1 is typically Orange/White. Knowing which harness lead and wire color to inspect is critical when checking for continuity or voltage pulses from the PCM to the injector.
• Cylinder 1 Location (HEMI V8) — The front-most cylinder on the driver's side of the engine.. Correctly identifying the cylinder is the first step for any diagnosis, such as swapping the ignition coil or inspecting spark plugs.
• G105 / G114 — These are common ground point identifiers for 2013-2018 Ram trucks, often located on the body near the battery or on the engine block.. A poor engine or PCM ground can cause erratic behavior, including misfires. Verifying that main ground connections are clean and tight is a crucial step when electrical causes are suspected.

Real Owner Repair Stories

• YouTube channel 'Dmitriy Sh. (2014 Ram 1500 5.7L HEMI) — Persistent P0301 code, rough running.
  ❌ Tried (didn't work) Replaced spark plugs, Replaced ignition coil on cylinder 1, Swapped fuel injectors between cylinders 1 and 2
  ✅ What actually fixed it Diagnosis with a pressure transducer revealed insufficient intake valve opening. The root cause was a worn camshaft lobe for cylinder 1, a classic HEMI failure. The fix required replacing the camshaft and all lifters.
• YouTube channel 'Code PO301 - Cylinder Misfire' (4th Gen Ram 1500 5.7L HEMI) — P0301 code appeared immediately after the engine was pressure washed.
  ✅ What actually fixed it Upon removing the ignition coil for cylinder 1, visible moisture was found inside the spark plug boot. The moisture was causing the spark to short to ground. The fix was to thoroughly dry the coil, boot, and spark plug well, then apply dielectric grease before reassembly.
• Reddit user 'Unclestanky' (2010 Ram 1500 5.7L HEMI) — P0301 check engine light, no major driveability issues.
  ❌ Tried (didn't work) Initially suspected ignition coil.
  ✅ What actually fixed it The problem was resolved by replacing the spark plugs.

"I Checked Everything" — The Actual Cause

• In the context of a P0301 misfire, the equivalent of a 'smoke test clean' scenario is when spark, fuel, and basic compression tests all check out as good, yet the misfire persists. In one documented case on a 5.7L HEMI, the root cause was a worn intake camshaft lobe. A standard static compression test did not reveal the fault because the valve still sealed correctly; the problem was that it wasn't opening enough to let a full air/fuel charge into the cylinder. This type of fault can only be found with more advanced diagnostics like a dynamic in-cylinder pressure transducer test or by physically removing the intake and valve cover to inspect the cam and lifters.

Model Year Variations Within This Range

• 2019-2020: For the 6.7L Cummins, the engine was significantly updated. It features a compacted graphite iron (CGI) block, new cast aluminum pistons, and hydraulic lifters. Crucially, these models also use the Bosch CP4.2 high-pressure fuel pump, which has a higher failure rate than the CP3 pump used in earlier years. A CP4.2 failure can send metal debris through the entire fuel system, destroying the injectors.
• 2019-2020: For gasoline engines, the 5.7L HEMI was dropped from the 2500 line, leaving the 6.4L HEMI as the standard engine. The 6.4L HEMI was paired with the more modern and efficient ZF 8-speed automatic transmission, replacing the previous 6-speed.