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Service bulletins for the 2021 Hyundai Sonata

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

109 on file from NHTSA, as of 2026-10-19.

About C1835 on the 2021 Hyundai Sonata: what the code means, and the bulletins and recalls about the same components.

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Only bulletins with trouble code: C1835 are shown. Show all

Bulletins, newest first
22-01-018H2022-03-08. Service bulletin. EQUIPMENT:ELECTRICAL; ENGINE AND ENGINE COOLING. Certain 2020-22MY Sonata (DN8a) and 2021-22MY Santa Fe (TMa) vehicles equipped with 2.5L engine may exhibit a MIL with DTC(s): • P2074: Mass Airflow Sensor Plausibility • P2074F0: Manifold Absolute Pressure/Mass Air Flow - Throttle Position Correlation at Lower Load • P2074F1: Manifold Absolute Pressure/Mass Air Flow - Throttle Position Correlation at Medium or High Load Secondary DTC(s) below may also be stored: • C136081: ESP Irreversible Error • C161308: CAN Signal Error EMS • C161386: CAN Signal Error EMS • C169381: Blind-Spot Collision Warning – CAN signal failure - ESC • C174181: ESC Not Available VSM (Check ESC) • C183586: CAN Message Failure ESC/IEB Vehicles diagnosed with DTC(s) may also experience reduced engine performance and limited power reduction mode. The ECM software revises the logic to accurately detect the amount of air the engine is receiving.
21-01-075H2022-01-08. Service bulletin. ENGINE AND ENGINE COOLING:ENGINE:ENGINE CONTROL MODULE (ECU/ECM). Certain 2020-22MY Sonata (DN8a), 2021-22MY Santa Fe (TMa), and 2022MY Tucson (NX4/NX4a) vehicles equipped with 2.5L engine may exhibit a MIL with DTC(s): • P2074: Mass Airflow Sensor Plausibility • P2074F0: Manifold Absolute Pressure/Mass Air Flow - Throttle Position Correlation at Lower Load • P2074F1: Manifold Absolute Pressure/Mass Air Flow - Throttle Position Correlation at Medium or High Load Secondary DTC(s) below may also be stored: • C136081: ESP Irreversible Error • C161308: CAN Signal Error EMS • C161386: CAN Signal Error EMS • C169381: Blind-Spot Collision Warning – CAN signal failure - ESC • C174181: ESC Not Available VSM (Check ESC) • C183586: CAN Message Failure ESC/IEB Vehicles diagnosed with DTC(s) may also experience reduced engine performance and limited power reduction mode. The ECM software revises the logic to accurately detect the amount of air the engine is receiving.

The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.