Given that "21-01" in automotive contexts typically refers to a or Recall Campaign from the year 2021 (or a campaign number), I have structured this as an investigative/technical overview based on public NHTSA and Honda records. If you meant a specific internal memo code (e.g., from a leak or specific market), please clarify. Honda 21-01: The Fuel Pump Failure Crisis Campaign: NHTSA 21V-014 / Honda Service Bulletin 21-01 Issue: Denso Low-Pressure Fuel Pump Impeller Failure Affected Vehicles: ~2.5 Million Globally (1.3 Million in the U.S.) The Core Problem Honda 21-01 addresses a manufacturing defect in the low-pressure fuel pump manufactured by Denso . The impeller (a plastic turbine inside the pump) was improperly molded. Due to low-density packing during production, the impeller absorbs moisture, swells, and deforms upon contact with fuel.