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Service bulletin 23-EM-009H

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.

The communication, as NHTSA indexes it (as of 2026-10-19)
TypeService bulletin
NHTSA id10247605
Published by NHTSA2023-12-22
Manufacturer's number23-EM-009H
Manufacturer's date2023-12-15
NHTSA componentENGINE AND ENGINE COOLING; POWER TRAIN

NHTSA's summary

Certain 2020-2023MY Sonata Hybrid (DN8 HEV) vehicles may exhibit coolant leakage, engine overheating, and white smoke from the exhaust due to an internal leak at the Exhaust Heat Recovery System (EHRS) portion of the center muffler assembly. Follow the procedure outlined in this bulletin to repair this condition after confirming EHRS is leaking internally.

The document

The document is the manufacturer's. This site does not hold it. NHTSA files a document at one of these two addresses; we have not asked NHTSA which.

Components

Engine, Transmission and driveline

Vehicles listed
HYUNDAI SONATA HYBRID2020, 2021, 2022, 2023 (the catalog's model; the bulletin names a series or trim of it)

Listing a model year does not mean every vehicle of it is concerned: the document says which.

Recalls for the same vehicles and component
23V5260002023-07-27. POWER TRAIN:AUTOMATIC TRANSMISSION:FLUID/LUBRICANT:PUMP
20225682022-10-06. Powertrain
22V7460002022-10-06. POWER TRAIN:AUTOMATIC TRANSMISSION

A recall listed here may apply to some of the same vehicles. Only the manufacturer can say whether it applies to one vehicle.

Other bulletins for the same vehicles and component
26-EM-016H TSB2026-10-14. Service bulletin. Some vehicles equipped with internal combustion engines may exhibit higher-than-expected engine oil consumption. This bulletin outlines the combustion chamber cleaning procedure for vehicles diagnosed with this condition. All internal combustion engines consume some engine oil during normal operation, depending on driving conditions and mileage, and this procedure should only be performed when deemed necessary based on inspection and diagnosis of the vehicle as outlined in TSB 26-EM-015H, Engine Oil Consumption – Inspection & Repair Guidelines, or the latest revision.
26-EM-015H TSB2026-10-13. Service bulletin. Certain vehicles equipped with internal combustion engines may exhibit higher-than-expected engine oil consumption. This bulletin provides the inspection and repair procedures for vehicles exhibiting this condition. All internal combustion engines consume engine oil as part of normal engine operation. Oil consumption rates may vary based on mileage, operating conditions, driving habits, and maintenance history. Hyundai recommends following the prescribed maintenance schedule and periodically checking the engine oil level using the dipstick to maintain proper engine oil level.
26-AT-005H TSB2026-06-16. Service bulletin. This bulletin provides information related to a Transmission Control Unit (TCU) software update for some vehicles equipped with an 8-speed wet dual clutch transmission (8WDCT). The software update revises the touch point learning variation, improving drivability and judder symptoms. Some 8WDCTs (indicated by a new part number) received an updated clutch spring. The correct TCU software update must be matched with the correct corresponding 8WDCT hardware, otherwise, drivability concerns may occur. This service procedure should be performed prior to any 8WDCT replacements done for drivability/judder concerns.
26-EE-003H TSB2026-04-21. Service bulletin. Some vehicles may exhibit difficulty starting in cold weather. This bulletin provides the procedure to perform an inspection on the starter magnetic switch for potential freezing and, if necessary, replace the starter magnetic switch (solenoid) assembly.
26-AT-001H TSB2026-03-11. Service bulletin. Some Santa Cruz (NXT), Santa Fe (TMA, MX5A), and Sonata (DN8A) models may require replacement of the 8-speed wet dual clutch transmission (8WDCT) when the vehicle sets one of the high pressure electric oil pump (HP EOP) DTCs listed below. This bulletin provides instructions to replace the 8WDCT.
26-EM-003H TSB2026-02-10. Service bulletin. Some Sonata (DN8, DN8A) vehicles may have DTCs P218100, P2181F0, and/or P2181F1 (Cooling System Performance) set in the Engine Control Module, resulting in an illuminated Check Engine warning lamp. Follow the procedure in this TSB to replace the Integrated Thermal Management (ITM) module and update both the Engine Control Module (ECM) and Transmission Control Module (TCM) if applicable. Follow the flowchart in this TSB to update the appropriate modules.
25-EM-007H TSB2026-01-06. Service bulletin. Some Elantra (CN7, CN7A), Kona (OS, SX2), and Sonata Hybrid (DN8 HEV) vehicles equipped with 2.0L engines may illuminate a warning lamp for DTC P218100 (Cooling System Performance) related to the Integrated Thermal-Management Module (ITM). Follow the service procedure in this bulletin to install a spring onto the thermostat within the ITM, in order to prevent premature opening, and perform an ECU software update on affected vehicles.
25-AT-001H TSB2025-06-03. Service bulletin. Certain Santa Fe (TMA) and Sonata (DN8/DN8A) vehicles equipped with 8-speed dual clutch transmissions (8DCT) may exhibit one of the DTCs listed below, related to the high pressure electric oil pump (HP EOP). Follow the procedures in this TSB to update the Transmission Control Unit (TCU) to the latest sensorless logic on affected vehicles, and then perform air bleeding and transmission learning.
25-EE-002H2025-05-02. Service bulletin. Certain Sonata (DN8) and Sonata (DN8A) vehicles may experience issues with the air conditioning due to damaged wiring in the engine room junction box. This bulletin provides instructions to replace the multi-fuse, reroute the damaged wiring using the blower wiring kit, and replace the fuse label.
24-AT-001H-12024-12-21. Service bulletin. This bulletin provides the procedure for updating the automatic transmission TCU (Transmission Control Unit) software to improve shift quality, judder and hesitation when accelerating.