P0301 on 2017-2021 Ford F-250 SD: Cylinder 1 Misfire Causes and Fixes

What's Unique About the 2017-2021 Ford F-250 SD

The 2017-2021 F-250 platform offers multiple powerful V8 engines: the 6.2L 'Boss', the 7.3L 'Godzilla', and the 6.7L Power Stroke diesel. While standard misfire causes like plugs and coils are common to all, specific issues are well-documented. For the 7.3L 'Godzilla' engine, early failure of spark plug wires due to high heat is a known problem, sometimes addressed by TSBs for related platforms like the F-53 chassis (TSB 20-2370). Some 2020 models with the 7.3L engine can also suffer from internal engine wear on camshafts and tappets (lifters), as noted in TSB 25-2572. 🎬 Watch: Expert breakdown of 7.3L camshaft and lifter delamination issues. Additionally, the 6.2L V8 is known to be susceptible to broken valve springs at higher mileage.

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
• Noticeable loss of engine power
• Check Engine Light is on or flashing
• Smell of gasoline from the exhaust
• Engine sounds different, may have a 'ticking' or 'popping' noise

Most Likely Causes

1. Faulty Ignition Coil or Coil Boot 🔴 High Probability → Shop Ignition Coil Coil-on-plug systems are common points of failure on modern engines due to heat and vibration. On the 6.2L V8, there are coils on the top spark plugs and separate wires for the lower plugs, adding complexity.
   How to confirm: Swap the ignition coil from cylinder 1 with another cylinder (e.g., cylinder 2). Clear the codes and run the engine. If the code changes to P0302, the ignition coil is faulty.
   Typical fix: Replace the faulty ignition coil and/or the spark plug boot. It's good practice to apply dielectric grease to the inside of the new boot to prevent moisture intrusion and corrosion.
   Est. part cost: $50-$120
2. Worn or Fouled Spark Plug 🔴 High Probability → Shop Spark Plug The 6.2L V8 uses two spark plugs per cylinder (16 total), increasing the chance of a failure. 🎬 See this DIY walkthrough for replacing all 16 spark plugs. Some 2017-2018 models with the 6.2L engine were subject to TSB 18-2188 for spark plug fuel fouling in cold weather, which could be resolved with a PCM software update.
   How to confirm: Remove the spark plug from cylinder 1 and inspect it for wear, carbon buildup, oil fouling, or damage to the electrode or porcelain. A cracked porcelain insulator is a common failure point.
   Typical fix: Replace the spark plug. It is recommended to replace all spark plugs at the same time for even performance and to avoid future misfires.
   Est. part cost: $10-$25 per plug
3. Failed Spark Plug Wire (7.3L and 6.2L) 🔴 High Probability → Shop Spark Plug The 7.3L 'Godzilla' engine has had notable issues with spark plug wires failing prematurely due to high engine heat. Ford issued TSB 21-2394 for some vehicles for this issue. 🎬 Watch: How to replace failing 7.3L Godzilla spark plug wires. The 6.2L also uses 8 spark plug wires for its lower set of plugs which can fail over time.
   How to confirm: Visually inspect the wire for any signs of burns, cracking, or arcing (white or black marks). With the engine running, you can sometimes see or hear the spark arcing from the wire to a metal part of the engine. An ohm test can also be performed on the wire to check its resistance against specifications.
   Typical fix: Replace the faulty spark plug wire. It is highly recommended to replace the entire set of wires at once.
   Est. part cost: $50-$150 for a full set
4. Faulty Fuel Injector 🟡 Medium Probability → Shop Fuel Injector
   How to confirm: Listen to the injector with a mechanic's stethoscope for a consistent clicking sound. You can also swap the injector with another cylinder to see if the misfire code follows it. For the 6.7L Power Stroke, injector balance rates can be checked with a diagnostic scan tool to identify a poorly performing injector.
   Typical fix: Replace the faulty fuel injector. On the 6.7L Power Stroke, this is a more involved job that may require special tools and programming.
   Est. part cost: $70-$150 (Gas), $200-$400+ (Diesel)
5. Engine Mechanical Failure (Valve Spring, Camshaft, Tappet/Lifter) ⚪ Low Probability A Ford Technical Service Bulletin (TSB 25-2572) notes that some 2020 7.3L models can have misfires due to excessive wear on camshafts and/or valve tappets (lifters). This is a known issue often attributed to oiling problems at idle. The 6.2L engine is also known for potential valve spring failures at higher mileage.
   How to confirm: A compression test and cylinder leak-down test are required to diagnose internal mechanical problems. This is best performed by a professional. A visual inspection with the valve cover removed may reveal a broken spring.
   Typical fix: Requires significant engine repair, such as replacing valve springs, lifters, or camshafts.
   Est. part cost: $500-$2000+

Rare But Worth Checking

• Under-torqued Crankshaft Pulley Bolt: → Shop Engine Crankshaft This is specific to a small number of 2017 models with a 6.8L engine built between Sept 2016 and Feb 2017, as per TSB SSM 46391. While the 6.8L is not a standard F-250 pickup engine, it was used in chassis cab models. This issue can cause multiple misfire codes.
• Vacuum Leak: A leak in a vacuum hose or intake manifold gasket can lean out the air-fuel mixture and cause a misfire. This would often be accompanied by other codes (like lean codes P0171/P0174) or affect multiple cylinders.
• Broken Fuel Injector Hold-Down Clamp (6.7L Power Stroke): → Shop Fuel Injector An earlier TSB for 2011-2012 6.7L engines (TSB 12-5-5) noted that a broken injector hold-down clamp could cause a misfire. While outside the specified year range, it's a known failure mode for this engine family.

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner to confirm P0301 and check for any other codes. Note if the Check Engine Light is steady or flashing.
2. Visually inspect the wiring and connector for the ignition coil and fuel injector on cylinder 1 (front passenger side). Look for damage or corrosion.
3. For 7.3L and 6.2L engines, inspect the spark plug wire for cylinder 1. Look for signs of arcing, burns, or physical damage.
4. To test the ignition system, swap the ignition coil from cylinder 1 with another cylinder (e.g., cylinder 2). Clear the codes and run the engine. If the code changes to P0302, the coil is bad.
5. If the misfire remains on cylinder 1, perform the same swap test with the spark plug.
6. If the ignition system is confirmed to be working, inspect the fuel injector. Listen for a steady clicking with a stethoscope. If in doubt, swap the injector with another cylinder to see if the misfire moves (this is more difficult and may not be feasible for DIYers on the 6.7L diesel).
7. If the misfire still persists on cylinder 1, the issue may be mechanical. Perform a cylinder compression test to check for issues like bad piston rings, valves, or a head gasket leak.
8. If compression is low, a cylinder leak-down test can help pinpoint the source of the compression loss (e.g., intake valve, exhaust valve, piston rings).

Parts You'll Likely Need

• Ignition Coil (OEM #DG-571 (Left side for 6.2L, may vary), DG-570 (Right side for 6.2L), LC3Z-12029-A (For 7.3L Godzilla)) — Ignition coils are a primary point of failure for misfire codes due to constant exposure to high heat and electrical stress.
  Trusted brands: Motorcraft, MSD, Denso
  OEM price range: $70-$120
  Aftermarket price range: $40-$80
• Spark Plug (OEM #SP-526 (For 6.2L V8), SP-589 / CYFS-12Y-T6 (For 7.3L Godzilla)) — Spark plugs are a wearable maintenance item. A worn or fouled plug cannot create the strong spark needed for proper combustion.
  Trusted brands: Motorcraft, NGK, Denso
  OEM price range: $15-$25
  Aftermarket price range: $8-$15
• Fuel Injector (OEM #W0133-2064787 (For 6.2L V8), FC3Z-9H529-A / CN6019 (For 6.7L Power Stroke, Cyl 1,2,7,8)) — A clogged or electrically failed injector will prevent the correct amount of fuel from entering the cylinder, causing a misfire.

Related Codes That Often Appear With This One

• P0300 — This code means 'Random Misfire Detected'. If the problem is intermittent or affects multiple cylinders (like a vacuum leak or low fuel pressure), P0300 may appear alongside P0301.
• P0316 — This code indicates a 'Misfire Detected on Startup (First 1000 Revolutions)'. It often appears with other P030x codes and helps pinpoint when the misfire is occurring.
• P0201 — This code indicates 'Injector Circuit/Open - Cylinder 1'. If it appears with P0301, it strongly suggests the problem is with the fuel injector on cylinder 1 or its wiring.

Technical Service Bulletins (TSBs) & Recalls

• TSB 25-2572: Addresses potential for misfire DTCs P0301-P0308 on some 2020 models with the 7.3L engine due to excess wear on camshafts and/or valve tappets.
• SSM 46391: Notes that certain 2017 6.8L engines may exhibit multiple misfire DTCs due to an under-torqued crankshaft pulley bolt.
• TSB 21-2394: Related TSB for some Ford vehicles addressing spark plug wire issues on the 7.3L engine, a known cause of misfires.
• TSB 20-2370: For 2020 F-53 Motorhome Chassis with the 7.3L engine, addresses misfires caused by damaged spark plug wires.

Platform-Specific Known Issues

• A known issue for some 2020 models with the 7.3L 'Godzilla' engine involves excessive wear on the camshaft and/or valve tappets (lifters), which can cause misfire codes including P0301. This was documented in Ford TSB 25-2572.
• The 6.2L 'Boss' V8 engine can be prone to broken valve springs as it accumulates mileage, a known cause for misfires on this specific engine.
• For the 7.3L 'Godzilla' engine, faulty spark plug wires have been a noted issue, sometimes failing prematurely and leading to misfires. Ford has issued TSBs for this on related platforms.
• A very specific issue for 2017 chassis cab models with the 6.8L engine (built between 10-SEP-2016 and 15-FEB-2017) is an under-torqued crankshaft pulley bolt, which can trigger multiple misfire codes as noted in TSB SSM 46391.
• On the 6.7L Power Stroke diesel, failure of the high-pressure fuel pump (CP4) can send metal debris through the fuel system, destroying the injectors and causing misfires. While not specific to cylinder 1, it's a catastrophic failure mode for this engine.

Mechanic-Grade Diagnostic Values

• Ignition Coil Primary Resistance (6.2L V8) — expected: OEM Motorcraft: ~0.55 Ohms. Aftermarket MSD: ~0.7 Ohms.. Failure: A reading significantly higher or lower than the specification, or an open circuit (infinite resistance).
• Ignition Coil Secondary Resistance (6.2L V8) — expected: OEM Motorcraft: ~5,500 Ohms. Aftermarket MSD: ~5,370 Ohms.. Failure: A reading significantly outside the expected range indicates a faulty coil winding.
• Spark Plug Wire Resistance (7.3L V8 'Godzilla') — expected: Varies by brand. Examples: ~30 ohms per foot for some performance brands, ~350-500 ohms per foot for others.. Failure: Extremely high resistance or an open circuit (infinite resistance) indicates a bad wire.
• Engine Compression — expected: Should be above 125 PSI with no more than a 10% variation between any two cylinders.. Failure: A cylinder with significantly lower compression than the others points to a mechanical issue like a bad valve, piston ring, or head gasket.

Hidden / Shadow Codes Worth Checking

• Mode $06, Test ID $A2-$AB: This is not a DTC, but a diagnostic monitor in the OBD-II system that tracks misfire counts for each cylinder. For a 10-cylinder engine, Test ID $A2 corresponds to Cylinder 1, $A3 to Cylinder 2, and so on. Even if a misfire isn't bad enough to set a P0301 code, counts may be visible here. (see via A professional scan tool capable of viewing Mode $06 data. It will show raw misfire counts per cylinder for the current and last 10 driving cycles.)

Scan Tool Commands That Help

• Ford IDS (Integrated Diagnostic System) or equivalent professional scanner (e.g., Snap-on, Autel): Power Balance Test (also known as Cylinder Contribution Test) — This is a crucial test for diagnosing misfires. The tool displays a graph showing the power contribution of each cylinder. A weak or dead cylinder will show a significant drop compared to the others. The technician can selectively disable individual fuel injectors to see the effect on engine RPM, confirming which cylinder is not contributing.

Wiring & Ground Locations

• G105 / G129 — In the passenger kick panel area, to the left of the fuse box. There are several factory grounding points on the metal frame.. Cylinder 1's ignition and fuel injector circuits are controlled by the PCM. A poor ground connection for the PCM or related engine sensors can cause erratic behavior, including misfires. The passenger kick panel area is a common and accessible place to check for clean, tight grounds when troubleshooting electrical issues.
• Engine Block to Frame/Body Ground Straps — There are multiple ground straps. One typically runs from the back of the cylinder head to the firewall on the passenger side. Another connects the engine block to the frame, often near the starter or engine mount.. The main engine ground is critical for the entire ignition system. The spark plugs rely on a solid ground path through the engine block. Corrosion or a loose connection on these main straps can cause weak spark and lead to intermittent or persistent misfires.
• PCM Connector C175B (Pin 75 - 5.4L example) — The main engine Powertrain Control Module (PCM), typically located on the firewall in the engine bay.. While specific pinouts vary by year and engine, the PCM connector is where the signal for the cylinder 1 ignition coil and fuel injector originates. For example, on an older F-250, pin 75 might control the #1 injector and pin 26 the #1 coil. A technician can back-probe this connector to verify the PCM is sending the correct signal, ruling out a faulty PCM driver circuit.

Real Owner Repair Stories

• Ford Truck Enthusiasts forum (2020 Ford F-250 with 7.3L V8, failure at 428 miles) — Check Engine Light came on, complete loss of power.
  ❌ Tried (didn't work) Initial dealer diagnosis was slow and did not identify the root cause.
  ✅ What actually fixed it The root cause was determined to be 'dropped a couple of lifters.' Ford replaced the entire engine assembly under warranty. This highlights the known camshaft/lifter issue in early 7.3L 'Godzilla' engines.
• YouTube User Repair Story (2020 F-250 Super Duty with 7.3L 'Godzilla' V8) — Flashing check engine light and popping sound under hard acceleration. Code P0300 (Multiple Cylinder Misfire) was stored.
  ❌ Tried (didn't work) Continuing to drive led to persistent symptoms.
  ✅ What actually fixed it The owner replaced all 8 spark plug wires with an aftermarket set. This resolved the misfire, improved shifting, and overall engine performance, pointing to the known issue of premature spark plug wire failure on this engine.

"I Checked Everything" — The Actual Cause

• In a documented case on a 2018 F-250 with a 6.2L engine, the truck was setting misfire codes P0301 and P0302 specifically under heavy load. While a vacuum leak might be suspected, the actual cause was a clogged catalytic converter for bank 1. The excessive backpressure prevented exhaust gases from escaping efficiently, leading to misfires as engine load increased. A borescope inspection confirmed the converter's internal honeycomb structure had broken apart.

Model Year Variations Within This Range

• 2017-2018 (built on or before May 2, 2018): Vehicles with the 6.2L engine in this range may have PCM software that causes spark plug fouling and misfires during cold starts. TSB 18-2188 was issued to correct this with a software update.
• 2020: The 7.3L 'Godzilla' V8 was introduced. Early production models are particularly noted for issues with spark plug wire failure due to heat and, more seriously, camshaft and valve tappet (lifter) wear, as documented in TSB 25-2572.