P0301 on 2017-2021 Ford F-350 SD: Cylinder 1 Misfire Causes and Fixes

What's Unique About the 2017-2021 Ford F-350 SD

While P0301 is a generic code, the 2017-2021 F-350 has specific issues documented by Ford that go beyond typical tune-up parts. For the 6.2L V8, TSB 18-2188 points to a cold-start fuel fouling issue that can cause misfires and may require a PCM software update. For both the 6.2L and 7.3L engines, TSB 25-2572 warns of potential major mechanical faults, including excessive camshaft and valve tappet wear. Furthermore, real-world owner reports indicate the 6.2L can suffer from broken valve springs causing a sudden misfire, and the 7.3L 'Godzilla' can have issues with faulty spark plug wires, as noted in TSB 20-2370 for some applications. This makes it crucial to perform a thorough diagnosis if new spark plugs and coils do not resolve the misfire.

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
• Engine hesitation or stumbling during acceleration
• Noticeable loss of power
• Flashing or solid Check Engine Light
• Smell of unburnt gasoline from the exhaust
• Hard starting

Most Likely Causes

1. Faulty Ignition Coil 🔴 High Probability → Shop Ignition Coil Coil-on-plug systems are common failure points on many modern engines due to constant exposure to heat and vibration.
   How to confirm: Swap the ignition coil from cylinder 1 with another cylinder (e.g., cylinder 2). Clear the codes and drive. If the code changes to P0302, the ignition coil is the faulty part.
   Typical fix: Replace the faulty ignition coil. It is often recommended to replace the corresponding spark plug(s) at the same time.
   Est. part cost: $40-$90
2. Worn or Fouled Spark Plug 🔴 High Probability → Shop Spark Plug
   How to confirm: After confirming the coil is good, remove the spark plug(s) from cylinder 1. Inspect for wear, carbon buildup, oil fouling, or a cracked insulator. A worn electrode or incorrect gap can cause a weak spark.
   Typical fix: Replace the spark plug. It is best practice to replace all spark plugs as a set if they are near the end of their service life. The 6.2L engine has two plugs per cylinder. 🎬 Watch: 6.2L Super Duty spark plug and coil replacement walkthrough
   Est. part cost: $10-$25
3. Faulty Spark Plug Wire (7.3L V8) 🟡 Medium Probability → Shop Spark Plug The 7.3L 'Godzilla' engine uses conventional spark plug wires, which can degrade over time from heat and vibration, causing a weak or intermittent spark. TSB 20-2370 was issued for some 2020 models due to damaged spark plug wires.
   How to confirm: Inspect the wire for cylinder 1 for any visible damage, cracks, or burns. Test the wire's resistance with a multimeter. An owner reported getting an electrical shock from a bad wire, confirming a loss of insulation.
   Typical fix: Replace the faulty spark plug wire. It is often recommended to replace all wires as a set.
   Est. part cost: $20-$40 per wire
4. Faulty Fuel Injector 🟡 Medium Probability → Shop Fuel Injector
   How to confirm: Listen to the injector with a mechanic's stethoscope; it should have a consistent clicking sound. You can also test the injector's resistance with a multimeter or swap it with another cylinder's injector to see if the misfire code follows.
   Typical fix: Replace the clogged or failed fuel injector. Sometimes running a high-quality injector cleaner can resolve minor clogging.
   Est. part cost: $70-$150

Rare But Worth Checking

• Excessive Camshaft and/or Valve Tappet Wear: → Shop Engine Camshaft This is a serious mechanical issue documented in Ford TSB 25-2572 for the 7.3L engine family. If basic ignition and fuel system checks do not resolve the misfire, a compression test and internal engine inspection may be necessary. Symptoms include a ticking/tapping noise, rough performance, and misfire codes P0301-P0308.
• Broken Valve Spring (6.2L V8): A known, though uncommon, failure on the 6.2L engine is a broken valve spring. This will cause a sudden and severe misfire that will not be resolved by replacing ignition components. Diagnosis requires removing the valve cover for inspection.
🎬 Watch: Tips and tricks for 6.2L spark plug and wire service
• Cold Start Fuel Fouling (6.2L V8): Per TSB 18-2188, some 2017-2018 6.2L engines may experience misfires on cold starts due to improper fueling strategy. The fix involves a PCM software update performed by a dealer.
• Under-torqued Crankshaft Pulley Bolt: → Shop Engine Crankshaft Ford SSM 46391 notes that certain 2017 models may have this issue, leading to multiple misfire codes. This can cause the crankshaft position sensor to read incorrectly. This should be investigated by a professional if other diagnostics fail. Note: The TSB summary mentions a 6.8L engine, which may be an error or apply only to specific chassis-cab models.
• Vacuum Leak: A leak in a vacuum hose, intake manifold gasket, or PCV system can introduce unmetered air and cause a lean misfire. This can be diagnosed with a smoke machine.
• Low Engine Compression: Caused by issues like a worn piston ring, leaking valve, or a bad head gasket. A compression test is required to diagnose this.

Diagnosis Steps

1. Read the code with an OBD-II scanner and note any other codes present. 🎬 See how to perform a Ford cylinder power balance test Freeze frame data can provide valuable context.
2. Identify Cylinder 1: It is the front-most cylinder on the passenger side.
3. Swap the ignition coil from cylinder 1 to cylinder 2. Clear codes and run the engine. If the code changes to P0302, the coil is faulty.
4. If the code remains P0301, inspect the spark plug wire (7.3L only) for damage or test its resistance. Swap with another cylinder's wire if possible.
5. If the code remains P0301, swap the spark plug(s) from cylinder 1 to cylinder 3. If the code changes to P0303, the spark plug was the issue. Remember the 6.2L has two plugs per cylinder.
6. If the code remains P0301, inspect the wiring and connector for the ignition coil and fuel injector on cylinder 1 for damage or corrosion.
7. Check the fuel injector on cylinder 1. Listen for its operation with a stethoscope or test its resistance.
8. If all of the above steps fail to identify the problem, proceed to more advanced diagnostics, such as checking for vacuum leaks with a smoke machine or performing an engine compression test to rule out mechanical issues.
9. Consult the vehicle-specific TSBs (18-2188 for 6.2L, 25-2572 for 7.3L) if no common cause is found.
10. If a sudden, severe misfire occurred on a 6.2L engine, consider a broken valve spring and inspect under the valve cover.

Parts You'll Likely Need

• Ignition Coil (OEM #6.2L (2017): AL3Z-12029-A/B (Motorcraft DG525/DG526); 6.2L (2018+): HL3Z12029B (Motorcraft DG-570); 7.3L: Not specified, coil-near-plug design.) — Ignition coils are a primary failure point for misfires and are a common first replacement part during diagnosis.
  Trusted brands: Motorcraft, NGK, Delphi
  OEM price range: $70-$110
  Aftermarket price range: $40-$90
• Spark Plug (OEM #6.2L: SP-526-X (Motorcraft); 7.3L: SP-586 or SP-589 (Motorcraft)) — As a routine maintenance item, spark plugs wear out and are a very common cause of misfires.
  Trusted brands: Motorcraft, Autolite, NGK
  OEM price range: $15-$30
  Aftermarket price range: $10-$25
• Spark Plug Wires (7.3L Engine) (OEM #LC3Z-12286-C (Motorcraft WR-6158); WR-6146, WR-6147 (Motorcraft)) — The 7.3L engine uses plug wires which can fail, causing misfires. This is a specific point of failure not present on the 6.2L's coil-on-plug design.
  Trusted brands: Motorcraft, Denso
  OEM price range: $25-$50
  Aftermarket price range: $15-$35

Related Codes That Often Appear With This One

• P0300 — If the misfire is intermittent or affects multiple cylinders, a P0300 (Random Misfire Detected) code may appear alongside P0301.
• P0302, P0303, etc. — If other cylinder-specific misfire codes are present, it may point to a systemic issue like the under-torqued crankshaft pulley bolt (SSM 46391), a vacuum leak, or a fuel delivery problem affecting an entire cylinder bank.
• P0316 — Misfire Detected on Startup (First 1000 Revolutions). This code often appears with other P030x codes and is specifically mentioned in TSB 18-2188 for the 6.2L engine and TSB 20-2370 for the 7.3L.

Technical Service Bulletins (TSBs) & Recalls

• TSB 25-2572: Addresses potential for misfire codes P0301-P0308 due to excess wear on camshaft and/or valve tappets, particularly relevant to the 7.3L engine family.
• SSM 46391: Points to an under-torqued crankshaft pulley bolt as a possible cause for multiple misfire codes on specific 2017 models (Note: TSB summary mentions a 6.8L engine).
• TSB 18-2188: Details a fix for cold-start misfires on 2017-2018 6.2L engines caused by fuel fouling, requiring a PCM update.

Platform-Specific Known Issues

• TSB 18-2188: 6.2L Cold Start Misfire: Some 2017-2018 F-Super Duty vehicles with 6.2L engines may exhibit a crank/no-start or misfire (P0300, P0301-P0308, P0316) in cold temperatures below 50°F (10°C). This may be due to spark plug fuel fouling. The fix requires a PCM software update.
• TSB 25-2572: Camshaft/Valve Tappet Wear: → Shop Engine Camshaft Some engines, particularly the 7.3L family, may experience rough performance and misfire codes (P0301-P0308) due to excessive camshaft and/or valve tappet wear. This requires professional mechanical diagnosis.
• TSB 20-2370: 7.3L Spark Plug Wire Damage (F-53 Chassis): → Shop Spark Plug Some 2020 F-53 Motorhome Chassis vehicles with the 7.3L engine built on or before 28-Sep-2020 may exhibit misfires on cylinders 1-4 (P0301-P0304) due to damaged spark plug wires. The fix involves modifying an air baffle and replacing all 8 wires with updated part number LC3Z-12286-C.

Mechanic-Grade Diagnostic Values

• Ignition Coil Primary Resistance (7.3L) — expected: ~0.68 Ohms. Failure: Significantly higher or infinite resistance (open circuit).
• Ignition Coil Secondary Resistance (7.3L) — expected: ~4.8K Ohms. Failure: Significantly higher or infinite resistance.
• Spark Plug Wire Resistance (7.3L V8) — expected: Varies by brand; 30 to 500 Ohms per foot are common for aftermarket performance wires. OEM spec is typically under 1,000 ohms per foot.. Failure: Infinite resistance (open circuit) or excessively high resistance.
• Fuel Injector Resistance — expected: ~12.5 Ohms. Failure: A reading significantly outside this value or infinite resistance.
• Engine Compression — expected: Above 125 PSI, with no more than a 10-15% variation between cylinders.. Failure: Significantly lower pressure in cylinder 1 compared to others.
• Fuel Pressure (Key On, Engine Off) — expected: ~58-68 PSI. Failure: Low fuel pressure can indicate a weak fuel pump or a leak, causing a lean misfire.

Hidden / Shadow Codes Worth Checking

• Mode $06, TID $53 (or Ax): This is not a DTC, but a monitor within the OBD-II system that tracks misfire counts per cylinder during the current and previous 10 driving cycles. For Ford, Test ID (TID) $53 is often used for misfire data. On newer CAN-bus systems, these may be listed as Component IDs $A1 through $A8 (for V8), where $A1 corresponds to Cylinder 1. A high count for CID $01 or $A1 indicates cylinder 1 is misfiring, even if the threshold to set a P0301 code has not been met. (see via A scan tool that can access OBD-II Mode $06 data. This is available on many professional and high-end consumer scanners.)

Scan Tool Commands That Help

• Ford IDS, FORScan, high-end Snap-on/Autel: Power Balance Test — This is a live data test that graphically displays the RPM contribution of each cylinder. A cylinder that is misfiring will show a significant dip in the graph compared to the others. The tool also allows the user to manually disable individual fuel injectors to confirm which cylinder is at fault.
• Ford IDS, FORScan: Misfire Monitor Neutral Profile Correction — This procedure, also known as a 'crank relearn,' must be performed after major engine or transmission repairs, or replacement of the PCM or crankshaft position sensor. Failure to perform this relearn can cause the PCM to incorrectly interpret crankshaft speed variations as misfires, setting false P030x codes.

Real Owner Repair Stories

• YouTube channel 'WreckTech' (2020 Ford Super Duty with 7.3L 'Godzilla' V8) — Sudden severe misfire while on a camping trip, flashing check engine light.
  ❌ Tried (didn't work) Initial confusion as parts stores claimed the truck did not have spark plug wires.
  ✅ What actually fixed it The owner diagnosed a bad spark plug wire on cylinder 2 by starting the truck and pulling the wires off the coil packs one by one until he found one that was not arcing (and getting shocked by the good ones). He confirmed the bad wire and made a temporary repair using a spark plug wire from a junked Chevrolet Silverado to get home.
• YouTube channel 'The Car Doctor' (2013 Ford F-250 6.2L V8 (demonstrates a common issue in the 2017-2021 range)) — P0302 misfire code and a loud engine rattle from the right bank.
  ❌ Tried (didn't work) Assuming it was the most common failure (a broken valve spring).
  ✅ What actually fixed it Upon removing the valve cover, the technician found the roller tip on the number 2 exhaust rocker arm had failed and disintegrated. The fix was to replace the entire rocker arm assembly with an updated part, retrieve metal debris from the head, and change the oil and filter.

"I Checked Everything" — The Actual Cause

• If standard diagnostics like swapping ignition components, checking fuel injectors, and performing a vacuum/smoke test reveal no faults, the cause for P0301 on these trucks is often mechanical. For the 6.2L V8, a broken valve spring is a known issue that won't be found by these tests. For the 7.3L V8, excessive camshaft and lifter wear (per TSB 25-2572) is the likely culprit. Both require removing the valve covers for a visual inspection or performing a compression test.

When the Usual Fixes Don't Work

• While a P0301 with a ticking or rattling noise on a 6.2L V8 is very commonly a broken valve spring, it is not the only cause. In one documented case, the cause was a failed roller tip on the exhaust rocker arm, which presents with identical symptoms. This highlights the need for a full valvetrain inspection under the valve cover, rather than stopping after finding one potential cause.
• If a P0301 code returns immediately after replacing the spark plug and ignition coil on a 7.3L V8, do not assume the new parts are faulty. The underlying cause is very likely the known camshaft and lifter/tappet wear issue described in TSB 25-2572, which requires a mechanical inspection and repair.

OEM Part Supersession History

• AL3Z-12029-A/B (Motorcraft DG525/DG526) → HL3Z12029B (Motorcraft DG-570) — Part update for newer model years.
  Heads up: Applies to the 6.2L V8. The DG-570 coil is specified for 2018 and newer F-350 SD models.
• Unknown (Original-fitment spark plug wires) → LC3Z-12286-C (Motorcraft WR-6158) — To address wire damage from contact with an air baffle.
  Heads up: This part update is specified in TSB 20-2370 for 2020 7.3L engines in the F-53 Motorhome chassis but is a good indicator of a known issue with the original wires. The fix also requires modifying the air baffle.

Model Year Variations Within This Range

• 2017 vs 2018-2021: The ignition coil for the 6.2L V8 engine changed. 2017 models use Motorcraft DG525/DG526, while 2018-2021 models use Motorcraft DG-570.
• 2020 (7.3L Engine): Per TSB 20-2370, some 7.3L engines built on or before Sept 28, 2020 (in F-53 chassis) were prone to spark plug wire damage. The repair involves replacing the wires with an updated part number and modifying an engine bay air baffle.