P0302 on 2022-2025 Genesis GV70: Cylinder 2 Misfire Causes and Fixes

What's Unique About the 2022-2025 Genesis GV70

For the 2022-2025 Genesis GV70 with the 2.5L Turbo engine, a P0302 code is frequently not a hardware problem. Genesis has issued a Technical Service Bulletin (TSB 25-01-051G) and a related service campaign (914G) because the original ECM software is overly sensitive and can incorrectly flag a misfire, especially during a cold start. The official fix is a simple software update performed by a dealer, which should be the first step in diagnosis for any owner of a 2.5T model. This campaign was initiated because the California Air Resources Board determined the vehicles could release excess pollutants.

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 or vibrating idle, especially on a cold start
• Hesitation or stumbling during acceleration
• Reduced engine power
• Poor fuel economy
• A smell of gasoline from the exhaust

Most Likely Causes

1. ECM Software Requires Update (2.5T Engine) 🔴 High Probability The original factory software for the Theta III 2.5L T-GDI engine has overly sensitive misfire detection logic, as acknowledged by Genesis in TSB 25-01-051G and Service Campaign 914G. This is particularly common during cold starts.
   How to confirm: Contact a Genesis dealer with your Vehicle Identification Number (VIN). They can confirm if Service Campaign 914G is open for your vehicle. This is often the first and only fix needed, as reported by many owners.
   Typical fix: A Genesis dealer will update the Engine Control Module (ECM) software with improved misfire logic. This service is provided at no cost to the owner under the service campaign and takes about 30-45 minutes.
   Est. part cost: $0
2. Faulty Ignition Coil 🟡 Medium Probability Ignition coils are a common failure point on most modern direct-injection engines. Heat and vibration can cause the internal windings to break down over time, leading to a weak or absent spark.
   How to confirm: Perform an 'ignition coil swap test.' Move the ignition coil from cylinder 2 to another cylinder (e.g., cylinder 1). Clear the codes and drive the vehicle. If the code changes to P0301, the ignition coil is confirmed to be faulty. Cylinder 2 is the second from the front of the engine (passenger side).
   Typical fix: Replace the faulty ignition coil. It is often recommended to replace all four coils at the same time for preventative maintenance, though not strictly necessary.
   Est. part cost: $40-$80
3. Worn or Fouled Spark Plug 🟡 Medium Probability Spark plugs are a normal wear-and-tear item with a finite lifespan. Carbon buildup, common in GDI engines, can also foul the plugs, leading to a weak or inconsistent spark. The service interval for spark plugs on the 2.5T is typically around 48,000 miles.
   How to confirm: After ruling out the ignition coil, remove the spark plug from cylinder 2. Inspect it for wear (worn electrode), damage (cracked porcelain), or heavy deposits of carbon or oil. Compare it to a new plug.
   Typical fix: Replace the spark plug in cylinder 2. It is best practice to replace all spark plugs as a set to ensure even performance and avoid future misfires.
   Est. part cost: $15-$30 per plug
4. Faulty Fuel Injector ⚪ Low Probability While less common than ignition components, GDI fuel injectors operate under very high pressure and can become clogged or fail electronically. Several GV70 owners have reported needing fuel injectors replaced to solve persistent misfire codes, even after the ECM update. In some cases, an injector seal can fail due to temperature changes, causing an improper fuel flow.
   How to confirm: This is a more advanced diagnosis. A professional technician can perform a fuel injector balance test or analyze fuel trim data. A DIY method involves listening to the injector with a mechanic's stethoscope to ensure it's clicking. A technician noted that on these models, the Multi-Port Injection (MPI) injector can sometimes be the cause, not the GDI injector. 🎬 See this walkthrough on how to replace the MPI injector.
   Typical fix: Replace the faulty fuel injector. Some dealers have opted to replace all four injectors as a set under warranty to resolve the issue definitively. This is a more labor-intensive and expensive job than coils or plugs.
   Est. part cost: $100-$250

Rare But Worth Checking

• Low Fuel Pressure: A recall (NHTSA #23V630000, Campaign 022G) was issued for a faulty low-pressure fuel pump on 2022-2023 models that can cause a loss of power. While this typically causes random misfires (P0300) or stalling, it could potentially manifest as a single cylinder misfire initially.
• Low Engine Compression: This indicates a more serious internal engine problem, such as a bad valve, worn piston rings, or a blown head gasket. A compression test is needed to diagnose this, which is unlikely on a newer vehicle but possible.
• Faulty Crankshaft Position Sensor: A faulty crankshaft position sensor can cause intermittent misfires that are difficult to diagnose. One technician documented a case on a GV70 2.5L where an intermittent cylinder 1 misfire that only occurred on startup was ultimately traced to a bad crankshaft sensor.

Diagnosis Steps

1. Read the code with an OBD-II scanner to confirm P0302 and check for any other codes.
2. (2.5T Engine Only) Contact a Genesis dealership with your VIN to check if Service Campaign 914G (ECM Software Update) is open for your vehicle. If it is, have this performed first as it is the most likely solution and is free of charge.
3. If the software update is not applicable or does not fix the issue, locate cylinder 2. On the 2.5T inline-4 engine, cylinders are numbered 1-2-3-4 from front (passenger side/belt side) to back (driver side/firewall side).
4. Swap the ignition coil from cylinder 2 with the coil from cylinder 1. Clear the codes and run the engine. If the code changes to P0301, the coil is bad and needs replacement.
5. If the code remains P0302, swap the spark plug from cylinder 2 with the plug from cylinder 1. Clear codes and run the engine. If the code changes to P0301, the spark plug is bad.
6. If the misfire still remains on cylinder 2, the issue is likely with the fuel injector or, in rarer cases, a mechanical engine problem like low compression or a sensor fault. At this point, professional diagnosis is recommended as fuel injector replacement is more involved.

Parts You'll Likely Need

• Engine Control Module (ECM) Software Update — This is the most common fix for P0302 on the 2.5T engine, addressing a known software logic issue.
  Trusted brands: Genesis
  OEM price range: $0 (under campaign 914G)
  Aftermarket price range: N/A
• Ignition Coil (OEM #27300-2T000) — A failed ignition coil is a very common cause for a single-cylinder misfire on most modern engines.
  Trusted brands: Hyundai/Genesis OE, NGK, Delphi
  OEM price range: $60-$100
  Aftermarket price range: $40-$80
• Spark Plug (OEM #18875-09085) — Spark plugs are a routine maintenance item that wear out over time, causing a weak spark and misfires.
  Trusted brands: Hyundai/Genesis OE (NGK or Denso), NGK, Denso
  OEM price range: $25-$40
  Aftermarket price range: $15-$30
• Fuel Injector (MPI) (OEM #35310-3NTB0) — In some documented cases, the Multi-Port Injector (not the GDI injector) has failed, causing misfires. This engine uses a dual-injection system.
  Trusted brands: Hyundai/Genesis OE
  OEM price range: $75-$105
  Aftermarket price range: N/A

Related Codes That Often Appear With This One

• P0300 — If the misfire is intermittent or affects other cylinders, a P0300 (Random/Multiple Cylinder Misfire) code may appear alongside P0302. The ECM software issue and fuel pump recall are known to cause misfires across multiple cylinders.
• P0301, P0303, P0304 — These codes indicate misfires in other cylinders (1, 3, and 4 respectively). Seeing them together with P0302 strengthens the case for a systemic issue like the ECM software or fuel delivery problem.

Technical Service Bulletins (TSBs) & Recalls

• 25-01-051G: Notes that 2.5L T-GDI engines may illuminate the Check Engine Light for misfire DTCs P0300-P0304 during a cold start and provides instructions for an ECM update.
• Service Campaign 914G: The customer-facing campaign related to TSB 25-01-051G, providing a free ECM software update to fix the misfire detection logic. It affects certain 2022-2025 GV70 models.

Platform-Specific Known Issues

• TSB 25-01-051G / Service Campaign 914G: Affects 2022-2025 GV70 models with the 2.5L T-GDI engine. The ECM may incorrectly detect misfires (P0300-P0304) during a cold start. The fix is a no-cost software update at a Genesis dealer.
• Recall 022G (NHTSA 23V630000): Affects 2022-2023 models. The low-pressure fuel pump impeller can deform in high heat, causing the pump to shut down and result in a loss of power. This should be checked by a dealer.

Mechanic-Grade Diagnostic Values

• Short-term fuel trim (STFT) on misfiring cylinder bank — expected: Close to 0% at idle.. Failure: A high positive percentage (e.g., +25% or higher) indicates the ECM is adding fuel to compensate for a lean condition, which can be caused by a clogged or failing injector.
• Misfire Counter (Live Data) — expected: Zero counts on all cylinders.. Failure: A rapidly increasing count on a specific cylinder (e.g., cylinder 2) confirms a persistent misfire that the ECM is detecting in real-time.

Hidden / Shadow Codes Worth Checking

• P030200: This is an extended format of the P0302 code, sometimes displayed by certain OBD-II scanners. It carries the same meaning: Cylinder 2 Misfire Detected. (see via Appears on some consumer-grade OBD-II scanners and can be seen in owner reports.)

Scan Tool Commands That Help

• Genesis GDS-Mobile: Current Data / Live Data Analysis — To confirm a misfire is actively occurring by monitoring the 'Misfire Counter' for each cylinder. It is also used to check 'Short Term Fuel Trim' and 'Long Term Fuel Trim' which can point towards a fuel delivery issue (injector) versus an ignition issue.
• Genesis GDS-Mobile: ECU Update — This is the specific dealer-level function used to perform Service Campaign 914G, which updates the ECM logic to prevent false misfire detection.

Real Owner Repair Stories

• Reddit user toastiela (2023 Genesis GV70 2.5T, ~17,000 miles) — Check engine light with a cylinder 4 misfire code (P0304).
  ❌ Tried (didn't work) Not specified, but the issue was persistent enough to require dealer intervention.
  ✅ What actually fixed it The dealership replaced all four fuel injectors under warranty to resolve the misfire.
• Reddit user Wooden_Tangerine_522 (2024 Genesis GV70 2.5T, 3,000 miles) — Rough feeling engine, then a check engine light for P030200 (Cylinder 2 Misfire).
  ❌ Tried (didn't work) Owner immediately sought dealer service.
  ✅ What actually fixed it The owner discovered an open service campaign (914G) for an ECM software update related to misfires. The implication is that this software update was the required fix.
• Technician Diagnostic Video (Pine Hollow Auto Diagnostics) (2022 Genesis GV70 2.5T) — Check engine light, shaking/vibration at idle, P0304 (Cylinder 4 Misfire).
  ❌ Tried (didn't work) Swapping ignition coil and spark plug from cylinder 4 to cylinder 1 did not move the misfire; it remained on cylinder 4.
  ✅ What actually fixed it Diagnosis using an oscilloscope and scan tool data (high positive fuel trims) pointed to a faulty MPI (Multi-Port Injection) fuel injector, not the GDI injector. The fix was to replace the failing MPI injector for cylinder 4.

When the Usual Fixes Don't Work

• While the most common fix is the ECM software update (Campaign 914G), multiple owner and technician accounts confirm that it does not solve all cases. In vehicles with persistent misfires after the update, the root cause has often been traced to faulty fuel injectors, specifically the MPI injectors in the engine's dual-injection system. One owner of a 2023 GV70 with 17,000 miles required all four fuel injectors to be replaced to solve a misfire code, demonstrating a hardware failure path that is separate from the software sensitivity issue.