2021-2025 Hyundai Elantra Fuel Tank Thudding Noise TSB

Symptoms

Owners of certain 2021-2025 Hyundai Elantra, Elantra N, and Elantra N-Line models may notice a distinct "thudding noise coming from the fuel tank assembly". This noise typically occurs when the vehicle is idling or on an incline. It is specifically linked to the operation of the Purge Control Solenoid Valve (PCSV) and is more prevalent when the fuel level is above 90% full. This "thudding noise coming from the fuel tank assembly" indicates a potential issue with the fuel tank assembly itself.

Diagnosis / Trigger Conditions

If you hear a "thudding noise coming from the fuel tank assembly" under the specified conditions—at idle or on an incline, with the PCSV operating, and the fuel tank more than 90% full—your vehicle may be experiencing the condition described in TSB 25-FL-003H. Technicians will confirm these conditions before proceeding with the repair.

Important Warnings

Hyundai provides specific instructions for technicians to ensure a proper repair and warranty claim. Owners should be aware of these details to ensure their service is handled correctly:

• "Do NOT re-use the rear exhaust muffler gasket, replace it with a new one." This is crucial for preventing exhaust leaks after the repair.
• "The newly supplied O-Ring of the fuel pump module top plate must be installed during installation of the fuel pump to the new fuel tank." This ensures a proper seal for the fuel pump.
• "Claim is subject to debit if the part is not returned." This note indicates that the old fuel tank assembly must be returned to Hyundai for warranty purposes.

Repair Procedure Summary

The repair outlined in TSB 25-FL-003H involves replacing the entire fuel tank assembly. The process begins with disconnecting the battery and recording radio presets. The rear muffler is then unfastened and separated from the exhaust to allow clearance for the fuel tank.

Once the fuel tank is lowered, the fuel pump module is removed, and any fuel is siphoned out. Essential components like fuel tank rubber pads, the heat protector shield, and the fuel filler hose are transferred from the old tank to the new one. The new fuel tank assembly is then installed, ensuring all fasteners are torqued to specification and a new exhaust gasket is used.

After reassembly, the battery is reconnected, the fuel system is primed, and the engine is started to check for proper operation and leaks. Finally, any triggered diagnostic trouble codes (DTCs) are cleared, and the radio presets are reprogrammed.

Required Tools or Parts

To address the "Hyundai Elantra fuel tank thudding" issue, the following parts and a special service tool are required:

• Fuel Tank Assembly: Part Number 31150-AA500FFF (Quantity 1)
• Fuel Pump O-Ring (Packing): Part Number 31115-0W000 (Quantity 1)
• Rear Exhaust Pipe Gasket (model-specific):
  • Elantra (CN7): 28751-1R000
  • Elantra (CN7A): 28751-3S000
  • Elantra N (CN7 N): 28751-A9200
  • Elantra (CN7 N-Line): 28751-2V000
• Fuel Pump Lock Ring Removal Tool: Special Service Tool (SST) 09310-B8100

Owner Action

If your 2021-2025 Hyundai Elantra, Elantra N, or Elantra N-Line exhibits a "thudding noise coming from the fuel tank assembly" under the conditions described, you should schedule an appointment with an authorized Hyundai dealership. This repair is covered under warranty, and the service procedure, identified by Operation Code 31150F06, has an estimated time of 1.5 hours.

NHTSA ID: 11018892