P0307 on 2020-2024 Ford F-350 Super Duty 7.3L V8: Cylinder 7 Misfire Causes and Fixes

What's Unique About the 2020-2024 Ford F-350 Super Duty

While a misfire code is generic, the 7.3L 'Godzilla' V8 in the 2020-2024 Super Duty has a well-documented weakness: the factory spark plug wires. They are highly susceptible to heat damage from the exhaust manifolds, leading to premature failure and misfires. Ford acknowledged this issue with TSB 20-2370 for some 2020 models and later released updated, more robust wire sets. Therefore, a P0307 code on this specific truck should immediately point to the ignition system, particularly the spark plug wire on cylinder 7. Furthermore, a persistent misfire on this engine, especially when accompanied by a ticking noise, can be a symptom of a more severe internal engine problem related to camshaft and lifter failure, which has been noted in multiple TSBs (like TSB 25-2572).

Symptoms You May Notice

• Rough or vibrating idle.
• Hesitation or stumbling during acceleration.
• Flashing or solid Check Engine Light.
• Noticeable loss of engine power.
• Increased fuel consumption.
• Audible ticking or tapping noise from the upper engine, which may point to a lifter/cam issue.

Most Likely Causes

1. Faulty Spark Plug Wire 🔴 High Probability → Shop Spark Plug The original equipment spark plug wires are a known failure point on the 7.3L Godzilla engine due to high heat from the exhaust manifolds causing the boots to degrade and arc. Ford issued TSB 20-2370 for this on some 2020 F-53 chassis and acknowledged the part issue for Super Duty trucks.
   How to confirm: Visually inspect the wire for cylinder 7 for any signs of arcing (white marks), melting, or physical damage. A common test is to spray a fine mist of water on the wire with the engine running and watch for sparks. The most definitive test is to swap the cylinder 7 wire with another cylinder (e.g., cylinder 5) and see if the code changes to P0305.
   Typical fix: Replace the spark plug wire for cylinder 7. It is highly recommended to replace all 8 wires with an updated OEM set (Part No. LC3Z-12286-C or a newer revision like LC3Z-12286-D) or a quality 🎬 Watch: See the redesigned ignition wires and how they compare. aftermarket set with better heat shielding.
   Est. part cost: $15-$40 for a single wire, $100-$250 for a full set.
2. Worn or Fouled Spark Plug 🟡 Medium Probability → Shop Spark Plug
   How to confirm: Remove the spark plug from cylinder 7. Inspect it for a worn electrode, incorrect gap, carbon buildup, or oil/fuel fouling. Compare it to a new plug.
   Typical fix: Replace the spark plug. If the plugs are near their service interval (60,000-100,000 miles), it is best practice to replace all 8 plugs.
   Est. part cost: $10-$25 per plug.
3. Failed Ignition Coil ⚪ Low Probability → Shop Ignition Coil
   How to confirm: Swap the ignition coil from cylinder 7 with an adjacent cylinder (e.g., cylinder 5). Clear the codes and run the engine. If the misfire code moves to P0305, the coil is the culprit.
   Typical fix: Replace the faulty ignition coil. The OEM part number is typically LC3Z-12029-A or LC3Z-12029-B (Motorcraft DG-587).
   Est. part cost: $50-$100.
4. Faulty Fuel Injector ⚪ Low Probability → Shop Fuel Injector
   How to confirm: After confirming the ignition system is working correctly, listen to the injector with a mechanic's stethoscope to hear if it's clicking. A professional can perform a fuel injector balance test to measure its flow rate.
   Typical fix: Replace the faulty fuel injector on cylinder 7.
   Est. part cost: $70-$150.

Rare But Worth Checking

• Camshaft/Valve Lifter Failure: → Shop Engine Camshaft While less common than ignition issues, the 7.3L Godzilla engine has a documented history of premature camshaft and valve lifter (tappet) wear, which can cause persistent misfire codes. This is a major mechanical failure often preceded by an audible ticking noise from the engine. TSBs like 25-2572 directly address this issue, linking P0301-P0308 codes to this wear. Diagnosis requires a compression test and may lead to a full engine replacement under warranty.
🎬 Watch: A teardown of a Godzilla engine with camshaft failure.
• Valve Spring Failure: In some instances, a P0307 can be caused by a broken valve spring. NHTSA ODI #11267686 describes a case where a vehicle experienced clattering, missing, and stalling due to a broken #7 intake valve spring which led to a dropped valve and internal engine damage.

Diagnosis Steps

1. Read the code with an OBD-II scanner to confirm P0307 and check for other codes like P0300 or P0316.
2. Listen for a rhythmic ticking/tapping noise from the engine. If present, this is a red flag for the known camshaft/lifter issue and warrants professional diagnosis, starting with an oil and filter inspection for metal debris.
3. Visually inspect the spark plug wire for cylinder 7 (second from front, passenger side). Look for any signs of heat damage, melting, or arcing (white dust on the boot).
4. If inspection is inconclusive, swap the spark plug wire from cylinder 7 with cylinder 5 (front-most, passenger side). Clear the codes and drive. If the code changes to P0305, the wire is bad.
🎬 See this walkthrough on diagnosing and solving a Godzilla misfire.
5. If the code remains P0307, swap the ignition coil from cylinder 7 with cylinder 5. Clear codes and drive. If the code changes to P0305, the coil is bad.
6. If the code still remains P0307, remove and inspect the spark plug. Replace it if it's worn, fouled, or damaged.
7. If all ignition components test good, the issue may be fuel-related. Listen for a steady clicking from the cylinder 7 fuel injector using a mechanic's stethoscope.
8. If ignition and fuel systems seem okay, a compression test should be performed on cylinder 7 to rule out mechanical engine problems. Low compression strongly suggests an internal issue like the aforementioned lifter/camshaft failure.

Parts You'll Likely Need

• Spark Plug Wire Set (OEM #LC3Z-12286-C (or newer revision like -D)) — This is the most common cause of misfires on the 7.3L Godzilla V8 due to heat degradation of the original wires. The part number listed is an updated, more robust version from Ford.
  Trusted brands: Motorcraft, MSD, Granatelli, Taylor
  OEM price range: $120-$180
  Aftermarket price range: $100-$250
• Spark Plug (OEM #SP589 (Motorcraft)) — A standard wear item and a primary cause of misfires. It's best practice to replace the plug when replacing the wire or coil.
  Trusted brands: Motorcraft, NGK, Autolite
  OEM price range: $15-$25
  Aftermarket price range: $8-$20
• Ignition Coil (OEM #LC3Z-12029-A / LC3Z-12029-B (Motorcraft DG-587)) — While less common than the wire, a failed coil will cause a misfire on a single cylinder. It's the next logical part to replace if the wire and plug are good.
  Trusted brands: Motorcraft, NGK, MSD
  OEM price range: $60-$100
  Aftermarket price range: $40-$80

Related Codes That Often Appear With This One

• P0300 — If the spark plug wire issue is severe or multiple wires are failing, a 'Random/Multiple Cylinder Misfire' code may appear alongside the specific cylinder code.
• P0316 — This code for 'Misfire Detected on Startup (First 1000 Revolutions)' often accompanies a specific cylinder misfire code if the problem is most apparent right after starting the engine.

Technical Service Bulletins (TSBs) & Recalls

• TSB 20-2370: Addresses misfires on some 2020 7.3L engines in the F-53 Motorhome Chassis due to damaged spark plug wires, instructing technicians to replace all 8 wires with an updated part (LC3Z-12286-C) and modify an air baffle.
• TSB 25-2572: Addresses an upper engine ticking/tapping noise and/or misfire DTCs (P0301-P0308) on 7.3L engines due to excessive wear on the camshaft and/or valve tappets (lifters).
• TSB 21-2158: Notes that some vehicles may exhibit a lack of power and an illuminated MIL with P0307 and other codes due to software parameters within the PCM.
• TSB 22-2464: Indicates that vehicles equipped with a 5.0L engine may store P0307 due to various strategies within the PCM software, requiring a correction of the condition.
• TSB 18-2058: Describes an illuminated MIL with codes P0316 and P0307 stored in the PCM, even when the vehicle exhibits no drivability concerns.
• Bulletin #16-0039: Mentions that engines may exhibit an illuminated MIL with DTC P0307 present in the PCM memory with no other drivability symptoms.

Platform-Specific Known Issues

• Premature Spark Plug Wire Failure: The original wires on 2020 and some later models are known to fail due to heat from the exhaust manifold, causing misfires. Ford issued TSB 20-2370 for this on some chassis and later introduced improved parts.
• Camshaft/Lifter Wear: Some 7.3L engines, particularly earlier models (2020-2022), have experienced premature failure of the camshaft and valve lifters, which can present as a misfire code. This is a major repair, often requiring engine replacement, and is frequently preceded by an audible engine tick. Ford has issued multiple TSBs (e.g., 25-2572) related to this issue.

Mechanic-Grade Diagnostic Values

• Spark Plug Wire Resistance — expected: OEM spec is typically under 1,000 ohms per foot. Aftermarket performance wires can be around 30-500 Ohms per foot.. Failure: An excessively high resistance reading (in the kilo-ohms) or an open circuit (OL) on a multimeter indicates a bad wire.
• Fuel Injector Coil Resistance — expected: Typically between 11.0 and 18.0 Ohms for a high-impedance injector.. Failure: A reading significantly outside the expected range, or an open (OL) or shorted (near 0 Ohms) circuit.
• Fuel Pressure (KOEO - Key On, Engine Off) — expected: 58 to 60 PSI.. Failure: Low fuel pressure can cause lean conditions and misfires across multiple cylinders.

Scan Tool Commands That Help

• Ford IDS (Integrated Diagnostic System): Power Balance Test — This function allows a technician to disable one cylinder at a time while monitoring the drop in engine RPM. If disabling cylinder 7 causes little or no change in RPM, it confirms that cylinder is not contributing power, pinpointing the misfire without having to swap parts.

Real Owner Repair Stories

• YouTube channel 'Motorized Co.' (2020 Ford F-250 Super Duty 7.3L Godzilla V8) — Truck started popping under hard acceleration, flashing check engine light, rough idle, and a P0300 (multiple misfire) code was stored, along with a non-stored code for cylinder 2.
  ❌ Tried (didn't work) The owner initially thought the rough idle was normal for the truck.
  ✅ What actually fixed it The owner replaced all 8 spark plug wires with an aftermarket set from O'Reilly's. This completely resolved the misfire, smoothed out the idle, improved shifting behavior, and increased power delivery.
• YouTube channel 'WreckTech Shop Truck' (2020 Ford Super Duty with 7.3L Godzilla V8) — Misfire on cylinder 2 during a camping trip.
  ❌ Tried (didn't work) The owner confirmed the misfire by pulling coil connections one by one while the engine was running and observing no spark from the #2 coil wire.
  ✅ What actually fixed it As a temporary fix in the field, the owner scavenged a spark plug wire from a junked Chevrolet Silverado and adapted it to fit. This immediately solved the problem, confirming the original Ford wire was the sole cause of the misfire.
• NHTSA ODI #11267686 — An owner reported that their engine was clattering, missing, stalling, and backfiring with a P0307 code. The dealer found a broken #7 intake valve spring and a dropped valve, necessitating a full engine replacement.

OEM Part Supersession History

• LC3Z-12286-A → LC3Z-12286-C, then LC3Z-12286-D — The original wires were prone to heat damage. The updated parts offer improved heat resistance to prevent arcing and premature failure.

Model Year Variations Within This Range

• 2020-2022: These earlier models are more susceptible to the camshaft/lifter failure issue. The problem was often attributed to a variable displacement oil pump that provided low oil pressure at idle. Ford later issued PCM updates to increase idle oil pressure and made internal revisions to mitigate this.
• 2023-2024: For the 2023 model year, Ford increased the 7.3L V8's torque from 475 lb-ft to 485 lb-ft through tuning improvements. These later models are also believed to have revised lifters and oiling system logic from the factory to reduce the risk of valvetrain failure.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Premature Camshaft/Valve Lifter Failure 🔴 High → Shop Engine Camshaft — Reported across 2020-2023 models, sometimes with mileage as low as 30,000. Seems more prevalent on earlier builds. Often starts as a light engine tick. (Ref: TSB 25-2572, TSB 25-2322)
• Spark Plug Wire Degradation 🟠 Medium → Shop Spark Plug — Very common on 2020-2021 models before updated parts were widely used. Failure due to heat from exhaust manifolds. (Ref: TSB 20-2370)
• Electrical Gremlins / Parasitic Battery Drain 🟠 Medium — Multiple owner reports of random electrical issues, including dead batteries, alarms going off, and infotainment screens freezing or going black. TSB 22-2443 addresses water intrusion into the battery junction box as one cause. (Ref: TSB 22-2443)
• 10-Speed TorqShift Transmission Issues 🟠 Medium — Some owners report harsh shifting, delayed engagement, or hunting for gears. While generally reliable, some units have required valve body replacement or software updates.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For this repair, a used ignition coil is a reasonable choice. It is a non-wear item that typically either works or doesn't, and can be easily tested by swapping its position. Other electronic sensors or modules could also be sourced from a donor vehicle.

Donor-vehicle mileage cap: roughly under 80000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• For an ignition coil, check for cracks in the plastic housing or corrosion on the electrical connector pins.
• Ensure the donor vehicle was not in a front-end collision or engine fire.
• Look for a donor vehicle with a clean engine bay, suggesting good maintenance.

OEM-only on this vehicle (don't cheap out):

• Spark Plug Wires: Given the well-documented failure of the original OEM wires, it is critical to buy the latest revised OEM part (Motorcraft) or a high-quality aftermarket set specifically designed for better heat resistance. A used set of wires is a major gamble and not recommended.

Aftermarket brands forum-validated for this vehicle:

• Spark Plug Wires: MSD, Granatelli, Taylor
• Ignition Coils: MSD, Top Street Performance (TSP)

Brands owners have reported issues with on this vehicle:

• Unbranded, no-name ignition components from online marketplaces are frequently reported to have high failure rates.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0300 — Random or multiple cylinder misfire code that may appear alongside P0307 if multiple spark plug wires are degrading from heat.
• P0305 — Cylinder 5 misfire; often used during diagnosis when swapping wires or coils from cylinder 7 to confirm if the fault follows the component.
• P0316 — Misfire detected on startup (first 1000 revolutions), which may accompany P0307 during initial diagnostic scans.
• P0301-P0308 — Companion misfire codes cited in TSB 25-2572 related to the same camshaft and valve tappet wear issues affecting the 7.3L engine.

Frequently Asked Questions