P0304 on the 2018 Hyundai Elantra
The bulletins listed name this code in NHTSA's summary, or are about the same components. A bulletin or a recall listed here may apply to the model year. None of it is a diagnosis.
Nobody has written a description of this code yet.
| 20-01-008H | 2020-03-07. Service bulletin. This bulletin provides information related to the Engine Control Module (ECM) software update for 2018 - 2019MY Elantra (AD/ADA) vehicles equipped with 2.0L engine. This software update includes cylinder imbalance learning logic optimization for Malfunction Indicator Light illumination with DTC P0300/P0301/P0302/P0303/P0304 (Cylinder “X” – misfire detected). |
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1 on file from NHTSA, as of 2026-10-19. See them in the bulletin list. A bulletin lists model years: read the document for which vehicles it concerns.