2021-2023 Hyundai Misfire DTC P030X TSB

Hyundai has released Technical Service Bulletin (TSB) 23-FL-002H-1, which supersedes TSB 23-FL-002H, to address misfire diagnostic trouble codes (DTCs) in specific 2021-2023 Hyundai Sonata, Santa Fe, Santa Cruz, and Tucson models. This bulletin specifically targets vehicles equipped with 2.5L GDI (Gasoline Direct Injection) non-turbo engines that are experiencing one or more misfire DTCs, commonly referred to as a "Hyundai misfire P030X", due to internal leaks in the GDI injectors.

This TSB provides a detailed diagnostic and repair procedure for technicians to identify and resolve the root cause of the misfires, ensuring proper engine performance and preventing potential long-term issues.

Symptoms

Owners of affected 2021-2023 Hyundai vehicles may notice a few key indicators that point to this issue. The most common symptom is the illumination of the check engine light on the dashboard. This light is typically accompanied by the storage of a misfire diagnostic trouble code (DTC) in the vehicle's engine control module.

If your vehicle is experiencing a "Hyundai misfire P030X" code, it suggests that one or more cylinders are not firing correctly. While the TSB focuses on internal GDI injector leaks, a misfire can also manifest as rough idling, reduced engine power, or decreased fuel efficiency.

Fault Codes / DTCs

The primary fault code associated with this issue is the generic misfire DTC P030X. This code indicates a misfire condition in one or more cylinders. The 'X' in P030X is a placeholder for the cylinder number, meaning it could be:

• P0301: Cylinder 1 Misfire Detected
• P0302: Cylinder 2 Misfire Detected
• P0303: Cylinder 3 Misfire Detected
• P0304: Cylinder 4 Misfire Detected

When these codes are present, especially in conjunction with the symptoms described, technicians should follow the TSB's diagnostic steps to confirm if an internally leaking GDI fuel injector is the cause.

Diagnosis

Diagnosing the internal GDI injector leak involves a specific procedure using the Hyundai Global Diagnostic System (GDS). The steps are as follows:

1. Connect to the GDS and navigate to the "DTC Analysis" and "ENGINE" menu. Record any stored DTCs, such as the "Hyundai misfire P030X", and the Freeze Frame Data. This data helps identify which cylinder(s) are affected. After recording, delete the DTCs.
2. From the GDS home screen, select "Data Analysis" and then the "ENGINE" menu. This allows for real-time monitoring of engine parameters.
3. Start the engine and monitor the fuel pressure readings displayed on the GDS. The system will show current fuel pressure and the set point value.
4. Shut off the engine and continue to monitor the fuel pressure. If the fuel pressure does not drop significantly after the engine is turned off, this TSB may not apply, and further diagnostic steps for misfires should be pursued. However, if the fuel pressure drops, it indicates a leak, and the GDI fuel injector(s) on the affected cylinder(s) should be replaced.

Repair Procedure Summary

The repair procedure outlined in TSB 23-FL-002H-1 focuses on replacing the faulty GDI fuel injector(s) and associated components. Technicians are instructed to:

1. Identify the specific GDI fuel injector(s) that are leaking based on the diagnostic results.
2. Follow the detailed repair procedures found in the shop manual under "Engine Control / Fuel System → Engine Control System → Injector → Repair procedures → GDI Injector."
3. During reinstallation, new combustion seals (part number 35312-04AA0) must be installed on all reused injectors. This ensures a proper seal and prevents future leaks.
4. The high-pressure fuel pipe (part number 35305-2S000QQH) must be replaced with a new part during the reassembly of the fuel rail.
5. If any injectors are replaced, new bolts (part number 11403-08556K) are required (1-4 depending on the number of injectors replaced).
6. Crucially, technicians must use the STUI system to take photos of the replaced injectors, the new high-pressure fuel pipe, new bolts, and reused injectors with new combustion ring seals. These photos, along with the last 6 digits of the VIN and the repair date written on paper, must be uploaded to STUI for documentation.
7. Upload the freeze frame data collected during diagnosis for future claim verification.

The primary replacement part for the injector itself is INJECTOR ASSY-FUEL (35310-2S000QQH). The warranty causal part is listed as 35310-2S000.

Required Parts

To perform this repair, the following parts may be required:

• INJECTOR ASSY-FUEL: Part Number 35310-2S000QQH (Must replace for any affected injector(s))
• PIPE-HIGH PRESSURE: Part Number 35305-2S000QQH (1 required for reassembly)
• COMBUSTION SEAL RING: Part Number 35312-04AA0 (Must replace for any reused injector(s))
• BOLT: Part Number 11403-08556K (1-4 required only for replaced injector(s))

Important Warnings

Hyundai has issued specific warnings regarding warranty claims related to this TSB:

• "All claims submitted that have incomplete, illegible, or missing documentation are subject to debit."
• "Claim is subject to debit if the part is requested and not returned."

These warnings emphasize the critical importance of following all documentation and parts return procedures precisely to ensure warranty claims are processed successfully.

Owner Action

If your 2021-2023 Hyundai Sonata, Santa Fe, Santa Cruz, or Tucson with a 2.5L GDI engine is displaying a check engine light and you suspect a "Hyundai misfire P030X" code, it is recommended to schedule an appointment with an authorized Hyundai dealership. The diagnostic and repair procedures outlined in TSB 23-FL-002H-1 should be performed by trained technicians.

This repair is typically covered under warranty for eligible vehicles. Ensure your dealership is aware of TSB 23-FL-002H-1 when you bring in your vehicle.

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Source: NHTSA ID: 10238377