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C1818 on the 2021 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.

This code is specific to a manufacturer and is not described here. Its meaning is in the manufacturer's service information.

Bulletins for this model year that name C1818
22-01-076H-12022-11-01. Service bulletin. Some 2021 ~ 2022MY Elantra (CN7, CN7a, CN7 HEV) vehicles may exhibit a condition with multiple warning lights displayed on the instrument cluster and various symptoms; multiple DTCs (Diagnostic Trouble Code), reduction in power steering assist, and not able to shift out of Park. Possible DTCs set are: • C181287 – CAN Time-out Gateway • C181208 – CAN Time-out Gateway • C180581 – LKAS CAN Signal Error • C181887 – CAN Time-out BCA • B109052 – TCU Missing Error This bulletin provides the service procedure to update the ICU (Integrated Central Control Unit) software to resolve the conditions stated above.
22-01-076H2022-09-27. Service bulletin. Some 2021 ~ 2022MY Elantra (CN7, CN7a, CN7 HEV) vehicles may exhibit a condition with multiple warning lights displayed on the instrument cluster and various symptoms; multiple DTCs (Diagnostic Trouble Code), reduction in power steering assist, and not able to shift out of Park. Possible DTCs set are: C181287 – CAN Time-out Gateway, C181208 – CAN Time-out Gateway, C180581 – LKAS CAN Signal Error, C181887 – CAN Time-out BCA, B109052 – TCU Missing Error This bulletin provides the service procedure to update the ICU (Integrated Central Control Unit) software to resolve the conditions stated above.
21-01-056H2021-08-07. Service bulletin. Some 2021 Elantra (CN7) vehicles may exhibit a condition with multiple warning lights displayed on the instrument cluster and various symptoms; multiple DTCs (Diagnostic Trouble Code), reduction in power steering assist, and not able to shift out of Park. Possible DTCs set are: • C181287 – CAN Time-out Gateway • C181208 – CAN Time-out Gateway • C180581 – LKAS CAN Signal Error • C181887 – CAN Time-out BCA • B109052 – TCU Missing Error

3 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.