P0301 on 2022-2025 Genesis GV70: Cylinder 1 Misfire Causes and Fixes

What's Unique About the 2022-2025 Genesis GV70

For the 2022-2025 Genesis GV70 equipped with the 2.5L T-GDI engine, this code has a very specific and well-documented cause. The manufacturer has issued Technical Service Bulletins indicating that misfires on cold starts can be due to the ECM's software logic being overly sensitive. Before replacing any parts on the 2.5L model, it is critical to check if this software update has been performed. While the 3.5L V6 can also experience this code, it is more likely to be from traditional causes like ignition coils or spark plugs. Additionally, a notable number of owners of the 2.5T model have reported early fuel injector failures causing misfires.

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
• Flashing or solid Check Engine Light
• Smell of unburned gasoline from the exhaust
• Vehicle entering 'safety mode' or limp mode with reduced power.

Most Likely Causes

1. Engine Control Module (ECM) Software Update Needed (2.5L T-GDI Only) 🔴 High Probability As per manufacturer TSB 25-01-051G and Service Campaign 914G, the original ECM software on 2.5L engines has overly sensitive logic that can incorrectly detect misfires, particularly during a cold start. This campaign was initiated because the condition could cause the vehicle to exceed federal and California air pollution standards.
   How to confirm: A Genesis dealership can check your vehicle's VIN against TSB 25-01-051G or Service Campaign 914G to see if the update is applicable and has not yet been performed. This affects certain 2022-2025 GV70 models, as well as some G80 and GV80 vehicles.
   Typical fix: The dealer reprograms the ECM with updated software logic. This is performed free of charge under the service campaign and takes about 30-45 minutes.
   Est. part cost: $0
2. Faulty Fuel Injector (2.5L T-GDI) 🟡 Medium Probability → Shop Fuel Injector A growing number of owners have reported issues with fuel injectors on the 2.5T engine, even at low mileage (e.g., 6,000-15,000 miles). One owner reported a dealer explanation that the injector seal can expand due to temperature changes, causing irregular fuel flow. This appears to be a pattern failure for this engine.
   How to confirm: This is difficult for a DIYer. A professional technician can perform a fuel injector balance test. Several owners on Reddit have confirmed that after reporting a P0301 code, the dealer diagnosed and replaced a faulty injector under warranty.
   Typical fix: Replace the faulty fuel injector. In many cases, dealers have opted to replace all four injectors as a preventative measure, even if only one has failed. This is typically covered under warranty.
   Est. part cost: $100-$200 per injector
3. Faulty Ignition Coil 🟡 Medium Probability → Shop Ignition Coil Coil-on-plug systems are a common failure point on modern direct-injection engines. Heat and vibration can cause the coil's internal windings to fail over time, leading to a weak or absent spark.
   How to confirm: The easiest DIY method is to swap the ignition coil from cylinder 1 with another cylinder (e.g., cylinder 2). Clear the codes and drive the vehicle. If the code changes to P0302 (Cylinder 2 Misfire), the ignition coil is confirmed to be faulty.
   Typical fix: Replace the faulty ignition coil. It is often recommended to replace all coils at the same time for preventative maintenance, but it's not required.
   Est. part cost: $40-$80
4. Worn or Fouled Spark Plug 🟡 Medium Probability → Shop Spark Plug
   How to confirm: Remove the spark plug from cylinder 1 and inspect it. Look for signs of heavy carbon buildup, oil fouling, a cracked insulator, or a worn-out electrode. Compare it to a new plug to see the difference.
   Typical fix: Replace the spark plug. It is best practice to replace all spark plugs as a set to ensure even performance and maintain service intervals.
   Est. part cost: $60-$120 for a set of four or six

Rare But Worth Checking

• Crankshaft Position Sensor: → Shop Engine Crankshaft Position Sensor A technician on YouTube documented an intermittent P0301 on a 2.5L GV70 that only occurred on cold start-up. After swapping coils and plugs with no change, an oscilloscope revealed a signal glitch from a faulty crankshaft position sensor 🎬 Watch: A technician diagnoses this rare intermittent misfire cause., which the ECM misinterpreted as a misfire.
• Vacuum Leak: A leak in a vacuum hose, PCV system, or intake gasket can introduce unmetered air, throwing off the air-fuel ratio and causing misfires. This would typically be accompanied by other codes (like P0171/P0174) or affect multiple cylinders.
• Low Compression: On a newer vehicle this is unlikely, but internal engine damage such as a leaking valve, damaged piston, or worn piston rings could cause a persistent misfire in one cylinder. This requires a mechanical compression test to diagnose.

Diagnosis Steps

1. Read all fault codes with an OBD-II scanner. Note if the Check Engine Light is steady or flashing and if other codes are present.
2. If the vehicle has the 2.5L T-GDI engine, your first step is to contact a Genesis dealer with your VIN. Inquire about open service campaigns, specifically Campaign 914G or TSB 25-01-051G, for an ECM update. This is the most common fix for cold-start misfires.
3. If no TSB applies or the update has been performed, locate cylinder 1. On the 2.5L inline-four, it is the cylinder closest to the front of the engine (radiator side). On the 3.5L V6, it is the front-most cylinder on the passenger side (right bank).
4. Swap the ignition coil from cylinder 1 with the coil from cylinder 2. Clear the codes, run the engine, and see if the misfire code moves to P0302. If it does, the coil is bad.
🎬 See this walkthrough for diagnosing misfires on Hyundai/Kia GDI engines.
5. If the code does not move, inspect the spark plug from cylinder 1. 🎬 Watch: Step-by-step troubleshooting for a Cylinder 1 misfire code. Look for wear, damage, or deposits. If it looks worn or fouled, replace it. Consider replacing all plugs as a set if they are near their service interval.
6. If the coil and plug are good, the issue may be with the fuel injector, especially on the 2.5L engine. A professional can confirm this, but you can use a scanner to observe fuel trims. A large positive fuel trim on the bank with cylinder 1 could indicate a clogged injector.
7. If all else fails, investigate rarer causes. Check for vacuum leaks (listen for hissing sounds, check PCV hoses). For intermittent start-up misfires, the crankshaft position sensor could be a suspect. A professional compression test can rule out mechanical engine problems.

Parts You'll Likely Need

• Ignition Coil (2.5L T-GDI) (OEM #27300-2T000) — This is a primary component of the ignition system and a common failure point for misfire codes after the ECM software has been ruled out. This part is shared with many Hyundai/Kia 2.5T models.
  Trusted brands: Hyundai/Genesis (OEM), NGK, Bosch, Delphi
  OEM price range: $60-$90
  Aftermarket price range: $40-$70
• Spark Plug (OEM #18875-09085) — Spark plugs are a routine maintenance item and can cause misfires when worn or fouled. They are an inexpensive and logical part to replace during diagnosis.
  Trusted brands: Hyundai/Genesis (OEM), NGK, HKS
  OEM price range: $20-$30 per plug
  Aftermarket price range: $15-$25 per plug
• Fuel Injector (2.5L T-GDI) (OEM #35310-2S001) — A documented failure point on the 2.5T engine leading to P030x codes, even at low mileage. Often replaced under warranty.
  Trusted brands: Hyundai/Genesis (OEM)
  OEM price range: $100-$200
  Aftermarket price range: $70-$150

Related Codes That Often Appear With This One

• P0300 — If the misfire condition is not isolated to one cylinder, a P0300 'Random/Multiple Cylinder Misfire' code may be stored. This is common with the 2.5L ECM software issue, as it can detect false misfires on several cylinders at once.
• P0302, P0303, P0304 — These codes indicate misfires in cylinders 2, 3, and 4, respectively. Seeing them alongside P0301 strongly suggests a systemic problem like the ECM software issue, low fuel pressure, or a major vacuum leak, rather than a single bad coil or plug.

Technical Service Bulletins (TSBs) & Recalls

• 25-01-051G: Addresses misfire DTCs P0300, P0301, P0302, P0303, or P0304 on 2.5L T-GDI engines in GV70, G80, and GV80 models, particularly during cold start. The fix is an Engine Control Module (ECM) update.
• Service Campaign 914G: A customer-facing campaign that implements the ECM software update from TSB 25-01-051G to correct the overly sensitive misfire detection logic.

Platform-Specific Known Issues

• A widely documented issue for the 2.5L T-GDI engine is a cold-start misfire that triggers codes P0300-P0304. This is addressed by Genesis TSB 25-01-051G and Service Campaign 914G, which involves a simple software update to the Engine Control Module (ECM).
• Multiple owners on the r/GenesisGV70 subreddit have reported P0301 codes on low-mileage 2.5T models (under 20,000 miles) that were ultimately resolved by replacing one or more fuel injectors under warranty.

Hidden / Shadow Codes Worth Checking

• Mode 6, Test ID $53 (example): Mode 6 data tracks misfire counts per cylinder for the current and previous driving cycles. Even if a misfire is not severe enough to set a P0301 code and turn on the check engine light, the counts will be stored here. A technician can view this data with an advanced scan tool to see if cylinder 1 has a higher misfire count than others, confirming an intermittent issue. (see via Advanced OBD-II Scan Tool with Mode 6 capability (e.g., Genesis GDS, Autel, Launch).)

Scan Tool Commands That Help

• Genesis GDS (Global Diagnostic System): Power Balance Test — When a rough idle or misfire is felt but the specific cylinder is uncertain. This function allows a technician to sequentially disable the fuel injector to each cylinder. When the injector for a good cylinder is disabled, the engine RPM will drop. When the injector for the misfiring cylinder (e.g., cylinder 1) is disabled, there will be little to no change in RPM, confirming it's the source of the problem.

Wiring & Ground Locations

• Engine Ground — On the passenger side of the engine compartment, there is a ground bolt on the chassis frame rail, indicated with a negative (-) symbol. This is a primary grounding point for engine components.. A poor ground connection at this point can cause intermittent and hard-to-diagnose electrical issues, including weak spark from the ignition coils, leading to misfire codes like P0301.
• Battery Location — The main 12V battery is located in the cargo area, under the floor panel. However, for jump-starting or testing, there are dedicated positive and negative terminals in the engine compartment.. Technicians should not go directly to the trunk to test battery voltage under load. Using the engine bay terminals is the correct procedure and ensures an accurate reading of the voltage being supplied to the engine's electrical system.
• Ignition Coil Fuse — In the engine compartment fuse panel, a 15A fuse labeled 'IGN COIL' protects the ignition coil circuit for the 2.5L T-GDI engine.. While a blown fuse would likely cause multiple misfires (P0300) rather than just P0301, checking this fuse is a quick and simple step to rule out a systemic power supply issue to the coils.

Real Owner Repair Stories

• Reddit user on r/GenesisGV70 (2023 Genesis GV70 with 13,000 miles) — Check Engine Light came on and the vehicle entered 'safety mode' (limp mode). The code was P030100.
  ❌ Tried (didn't work) The user took the vehicle directly to the dealer. Another user in the same thread with similar codes (P0300, P0301, P0302) was told by a different dealer that nothing could be done unless the issue could be replicated at the shop.
  ✅ What actually fixed it The dealership diagnosed a faulty fuel injector on cylinder 1. The dealer explained that they had seen cases where the injector seal expands with temperature changes, causing irregular fuel flow. They replaced all four fuel injectors under warranty, which resolved the issue.