P0303 on Genesis vehicles Cylinder 3 is misfiring

A model year is listed because the code is named in its own record — a bulletin filed against it, or an owner’s complaint about it — not because every one of these vehicles sets it. Counts are documents in NHTSA’s files, not failure rates.

Bulletins and campaigns Genesis filed with NHTSA whose summary names P0303. Quote the document number at the service desk — it is a diagnosis the maker has already written down.

• 25-01-051G DN Service campaign
  2025-08-06 · Engine
• Certain G80 (RG3), GV70 (JK1/JK1A), and GV80 (JX1) vehicles equipped with Theta III 2.5L T-GDI engine may illuminate the Check Engine Light as a result of misfire DTCs P0300, P0301, P0302, P0303, or P0304. The California Air Resources Board has determined that these vehicles may be releasing air pollutants which exceed Federal and California standards.
• 25-01-051G TSB Service campaign
  2025-08-06 · Engine
• Certain G80 (RG3), GV70 (JK1/JK1A), and GV80 (JX1) vehicles equipped with Theta III 2.5L T-GDI engines may illuminate the Check Engine Light as a result of misfire DTCs P0300, P0301, P0302, P0303, or P0304 during cold start. This bulletin provides instructions for updating the Engine Control Module (ECM).

A stored code names the test that failed, never the part that caused it. The record above is what Genesis and its owners have filed about it; the code’s page across every make has the whole file.