P0301 on 2021-2024 Genesis GV80: Cylinder 1 Misfire Causes and Fixes

What's Unique About the 2021-2024 Genesis GV80

For the 2021-2024 GV80 equipped with the 2.5L Turbo GDI engine, this code has a very specific and well-documented cause. Manufacturer Technical Service Bulletin (TSB) 25-01-051G states that misfires on cylinders 1-4 (P0301-P0304), especially during a cold start, can be due to a software error. The official fix is not a part replacement but an ECM software update performed by a Genesis dealer under Service Campaign 914G. While standard hardware faults like coils or plugs can still occur, the software issue is a primary, platform-specific consideration for the 2.5T model. For both the 2.5T and 3.5T engines, there are also increasing reports of premature fuel injector failure causing this code.

Diagnostic Flowchart

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

Symptoms You May Notice

• Check Engine Light is on or flashing
• Rough idle or shaking engine, sometimes felt through the whole vehicle
• Hesitation or stumbling during acceleration
• Noticeable loss of power
• Reduced fuel economy
• Smell of raw gasoline from the exhaust
• Engine goes into a reduced power "safety mode"

Most Likely Causes

1. ECM Software Update Needed (2.5L Engine Only) 🔴 High Probability A known issue documented in TSB 25-01-051G where the ECM's misfire detection logic is overly sensitive, especially on cold starts. This is addressed by Service Campaign 914G.
   How to confirm: Contact a Genesis dealer with your VIN to check if Service Campaign 914G or TSB 25-01-051G is open for your vehicle. This is the first and most important step for any 2.5T model with this code.
   Typical fix: Dealer performs an ECM software update. This is covered under a service campaign and should be free of charge.
   Est. part cost: $0
2. Faulty Ignition Coil 🟡 Medium Probability → Shop Ignition Coil Coil-on-plug systems are a common failure point on most modern engines. Heat and vibration cause the internal windings to eventually fail. This is a common diagnosis after the software update is ruled out.
   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 coil is faulty.
   Typical fix: Replace the faulty ignition coil. It is recommended to use OEM or high-quality brand replacements. The OEM part number for the 2.5T is 27300-2T000. The OEM part number for the 3.5T is 27301-3L100. 🎬 See this walkthrough on how to replace the ignition coil.
   Est. part cost: $50-$90
3. Worn or Fouled Spark Plug 🟡 Medium Probability → Shop Spark Plug Spark plugs are a regular maintenance item with a finite lifespan. Carbon buildup from GDI operation or normal electrode wear can prevent a strong spark, leading to incomplete combustion.
   How to confirm: Remove the spark plug from cylinder 1 and inspect it. Look for a worn electrode, heavy carbon deposits, or oil/fuel fouling. Compare it to a new plug.
   Typical fix: Replace the spark plug. It is best practice to replace all spark plugs at the same time to ensure consistent performance. OEM Part for 2.5T may be 18869-08110 (NGK SILKFR9A7G). OEM Part for 3.5T may be 18869-08100. 🎬 Watch: How to replace spark plugs on the V6 engine.
   Est. part cost: $20-$40 per plug
4. Faulty Fuel Injector 🟡 Medium Probability → Shop Fuel Injector Direct injection (GDI) systems operate under very high pressure, and injectors can become clogged or fail electronically. Several owner reports on the GV80 and GV70 point to injectors failing even at low mileage, requiring dealer replacement under warranty. A leaking GDI injector is especially dangerous as it can dilute engine oil, leading to catastrophic engine damage.
   How to confirm: This is difficult for a DIYer. A professional can perform an injector balance test or check resistance. A key symptom is a rising oil level that smells strongly of gasoline. In some cases, the ECM shuts off the injector, which can be seen on a high-end scan tool.
   Typical fix: Replace the faulty fuel injector. This is a more involved job on a GDI engine and may be best left to a professional. Some dealers have opted to replace all injectors on the affected bank.
   Est. part cost: $150-$250

Rare But Worth Checking

• Low-Pressure Fuel Pump Failure: A recall (No. 22V732000) was issued for some 2022-2023 GV80s for a failing low-pressure fuel pump. While this would typically cause multiple misfire codes (P0300), it could potentially manifest as a single cylinder misfire initially.
• Carbon Buildup on Intake Valves: Gasoline Direct Injection (GDI) engines are prone to carbon buildup on the back of the intake valves, as fuel is injected directly into the cylinder and does not wash the valves. This can disrupt airflow and cause misfires, typically at higher mileage.
• Faulty Crankshaft Position Sensor: → Shop Engine Crankshaft Position Sensor A technician working on a related GV70 2.5T with an intermittent P0301 traced the issue to a faulty crankshaft position sensor that had a glitch on startup. This is an uncommon but possible cause.
• Internal Engine Mechanical Issues: Problems like low compression from a bad valve, piston ring, or a stretched timing chain are possible but highly unlikely on a newer vehicle without other significant symptoms like knocking or smoke.

Diagnosis Steps

1. Read the code with an OBD-II scanner to confirm P0301 and check for any other codes.
2. (2.5L Engine Only) Contact a Genesis dealer with your VIN to check if TSB 25-01-051G / Service Campaign 914G is open for your vehicle. If it is, have the free ECM update performed. This is the most important first step.
3. If the ECM update is not applicable or does not resolve the issue, locate cylinder 1. On the 2.5L inline-4, it is the front-most cylinder (closest to the belts). On the 3.5L V6, it is the front-most cylinder on the passenger-side bank (Bank 1).
4. Perform the 'coil swap test'. Unplug and remove the 10mm bolt holding the ignition coil on cylinder 1. Do the same for cylinder 2 (the next one back on the 2.5T, or the front-most on the driver's side on the 3.5T). Swap their positions. Clear the codes and drive the vehicle. If the code returns as P0302, the ignition coil is bad and needs replacement.
5. If the code remains P0301 after the coil swap, inspect the spark plug in cylinder 1. Remove it with a spark plug socket and extension. Look for wear, damage, or heavy fouling. If it looks bad or is near its service interval, replace it (preferably as a full set).
6. If the coil and plug are good, check the oil dipstick. If the oil level is high and/or smells strongly of raw gasoline, do not drive the vehicle. This points to a leaking fuel injector which can cause severe engine damage.
7. If the above steps don't identify the issue, the problem is likely a faulty fuel injector, wiring issue, or a rarer cause. Professional diagnosis is recommended due to the complexity of testing GDI fuel systems.

Parts You'll Likely Need

• Ignition Coil (OEM #27300-2T000 (2.5T), 27301-3L100 (3.5T)) — A common cause of a dedicated single-cylinder misfire after the ECM update has been ruled out.
  Trusted brands: Hyundai/Genesis Genuine, NGK, Delphi
  OEM price range: $60-$90
  Aftermarket price range: $40-$70
• Spark Plug (OEM #18869-08110 (2.5T), 18869-08100 (3.5T)) — A standard wear item that can cause misfires when worn or fouled. Should be replaced as a set if near the end of their service interval.
  Trusted brands: NGK, Denso
  OEM price range: $25-$40
  Aftermarket price range: $15-$30
• Fuel Injector (High Pressure GDI) (OEM #35310-2T000 (2.5T)) — An increasingly common failure point on both engines, even at low mileage, causing persistent misfires.
  Trusted brands: Hyundai/Genesis Genuine
  OEM price range: $150-$250

Related Codes That Often Appear With This One

• P0300 — If the misfire is intermittent, affects multiple cylinders, or is caused by a system-wide issue like a fuel pump, a P0300 (Random/Multiple Cylinder Misfire) may be stored alongside P0301.
• P0302, P0303, P0304 — The TSB for the 2.5T engine specifically mentions that any of these codes can be triggered by the software issue. If multiple codes from the same bank are present, it strengthens the case for the ECM update being the root cause.
• P0201 — This code for 'Injector Circuit/Open - Cylinder 1' may accompany a P0301 if the misfire is caused by a failed fuel injector or a problem in its wiring.

Technical Service Bulletins (TSBs) & Recalls

• 25-01-051G: ECM SOFTWARE UPDATE – P030X MISFIRE. This TSB provides the procedure for a Genesis dealer to update the engine control module software to fix false misfire codes on 2.5L Turbo engines.
• Service Campaign 914G: This is the customer-facing campaign that implements the fix described in TSB 25-01-051G, including the ECM update and an emissions sticker.

Platform-Specific Known Issues

• TSB 25-01-051G / Service Campaign 914G: Affects 2021-2024 GV80 models with the 2.5L Turbo engine. An ECM software update is required to correct false misfire detection (P0300, P0301, P0302, P0303, P0304), particularly during cold starts. This is a no-cost repair at a Genesis dealer.
• Recall 22V732000 (NHTSA Campaign ID): Affects some 2022-2023 GV80 models. The low-pressure fuel pump may fail, leading to a loss of drive power. While this usually causes multiple misfires, it's a known issue to be aware of.
• Fuel Injector Failures: There is a pattern of owner complaints on forums for both the 2.5T and 3.5T engines regarding fuel injector failures at relatively low mileage (under 20,000 miles), leading to misfire codes.

Mechanic-Grade Diagnostic Values

• GDI Fuel Injector Resistance — expected: Generally 10-18 Ohms, with all injectors reading within 0.5 Ohms of each other.. Failure: A reading that is significantly higher, lower, or open-loop (infinite resistance) compared to the other injectors.
• Live Data - Fuel Trim (Lambda Correction) — expected: Close to 1.0 at idle on a healthy engine.. Failure: A technician noted a value of 1.239 on a misfiring GV70, indicating the ECM was attempting to add significant amounts of fuel to compensate for a lean condition or misfire.
• Live Data - Injection Time — expected: A specific millisecond value that varies with engine load.. Failure: On a misfiring GV70, a technician observed the injection time for cylinder 1 drop to zero, indicating the ECM had commanded the injector to shut off completely due to the persistent misfire.

Scan Tool Commands That Help

• Genesis GDS (Global Diagnostic System) or equivalent high-end scanner: Power Balance Test — This function allows a technician to individually disable one cylinder at a time and observe the corresponding drop in engine RPM. If disabling a cylinder causes little or no change in RPM, that cylinder is the one misfiring. This is used to confirm the location of the misfire reported by the P030x code.

Wiring & Ground Locations

• Engine Compartment Fuse Box — Located near the battery in the engine bay, under a cover.. Contains the 'ECU 4' fuse (20A) which powers the Engine Control Module (ECM), as well as other critical engine management relays and fuses that could be related to ignition or fuel system faults.
• Injector #1 Control Signal Pin — Pin 9 on the ECM harness connector [CGG-K].. This is the specific pin on the Engine Control Module that sends the control signal to the fuel injector for cylinder 1. A technician can use this pin to test for a signal from the ECM or check for continuity/shorts in the wiring harness between the ECM and the injector.
• G01 Engine Compartment Ground — Located on the left fender of the engine compartment.. A poor engine ground can cause a wide range of difficult-to-diagnose electrical issues, including weak spark or erratic sensor readings that could lead to a misfire code.

Real Owner Repair Stories

• Reddit user in /r/GenesisGV70 (2023 GV70 2.5T, 13,000 miles) — Check Engine Light came on and the engine went into a reduced power "safety mode".
  ❌ Tried (didn't work) Directly taken to the dealer.
  ✅ What actually fixed it The dealer identified a faulty fuel injector. The stated cause was the injector seal getting stuck due to temperature changes, causing irregular fuel flow. The dealer replaced all 4 injectors under warranty to resolve the P0301 code.
• Reddit user in /r/GenesisGV70 (2023 GV70 S/P 2.5T, 6,000 miles) — Persistent Check Engine Light with code P030100. Vehicle was reportedly running fine otherwise.
  ❌ Tried (didn't work) Dealing with slow dealership service response.
  ✅ What actually fixed it After the car was towed to the dealer, they confirmed a bad fuel injector. The single faulty injector was replaced under warranty, which resolved the code.
• Reddit user in /r/GenesisGV70 (2023 GV70 2.5T Advanced, 26,000 miles) — Check Engine Light came on during a morning start-up, with a dash message about a potential engine control system issue.
  ❌ Tried (didn't work) Directly taken to the dealer for diagnosis.
  ✅ What actually fixed it The dealer diagnosed a bad 'lower' fuel injector. It was replaced under warranty, and the repair was completed in 24 hours.

Model Year Variations Within This Range

• 2024: For the 2024 model year in some markets (like Australia), Genesis dropped the 2.5L Turbo engine option from the GV80 lineup, making the 3.0L diesel and 3.5L V6 the only available engines. This means the TSB related to the 2.5T ECM update would not apply to these specific 2024 models.
• 2023: For the 2023 model year, the rear-wheel-drive option for the 2.5T model was discontinued, making all GV80s all-wheel-drive only. This does not directly affect the P0301 cause but is a notable platform change within the specified year range.
• 2025 (Facelift): A significant facelift is expected for the 2025 model year, which will include redesigned consoles, a new 27-inch OLED screen, and potentially powertrain changes with the introduction of a GV80 Coupe model. While outside the 2021-2024 range, it's important to note that diagnostics and parts may differ significantly for these newer models.