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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.

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Only bulletins with component: Transmission and driveline are shown. Show all

Bulletins, newest first
26-AT-005H TSB2026-06-16. Service bulletin. POWER TRAIN. 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-AT-001H TSB2026-03-11. Service bulletin. POWER TRAIN. 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.
25-AT-001H TSB2025-06-03. Service bulletin. POWER TRAIN. 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.
24-AT-001H-12024-12-21. Service bulletin. POWER TRAIN. This bulletin provides the procedure for updating the automatic transmission TCU (Transmission Control Unit) software to improve shift quality, judder and hesitation when accelerating.
24-AT-002H2024-04-16. Service bulletin. POWER TRAIN. This TSB provides a procedure to diagnose and replace, if necessary, an automatic transmission with Incorrect Ratio DTC (transmission clutch slip in gear above limit) listed on Page 2.
24-FL-002H2024-03-05. Service bulletin. POWER TRAIN; ENGINE AND ENGINE COOLING:ENGINE:ENGINE CONTROL MODULE (ECU/ECM); ENGINE AND ENGINE COOLING. This bulletin provides the procedure to update the Engine Control Module (ECM) and/or the Transmission Control Module (TCM) for 2020-2023MY Sonata (DN8/DN8a) vehicles to improve operation of the Idle Stop and Go (ISG) system. Under certain circumstances the vehicle may not restart after the ISG system has engaged and requires a manual restart due to the lack of intake manifold pressure recovery.
24-AT-001H2024-03-05. Service bulletin. POWER TRAIN. This bulletin provides the procedure for updating the automatic transmission TCU and ECU software (Santa Fe ONLY) to improve shift quality, judder with ISG enabled and hesitation when accelerating.
23-EM-009H2023-12-22. Service bulletin. ENGINE AND ENGINE COOLING; POWER TRAIN. 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.
23-01-093H2023-12-22. Service bulletin. ELECTRICAL SYSTEM; POWER TRAIN. This bulletin provides the procedure to update the Hybrid Control Unit (HCU) and Dual Automatic Temperature Control (DATC) software to help improve coolant flow to the Exhaust Heat Recovery System (EHRS).
23-AT-006H-22023-11-30. Service bulletin. POWER TRAIN. This TSB provides information to diagnose the push button shifter operation.
23-AT-008H-12023-10-02. Service bulletin. POWER TRAIN. If you are servicing an 8-speed front-wheel-drive vehicle equipped with automatic transaxle with one or more of the DTC or symptoms listed below, refer to the Service Procedure to diagnose the condition. • DIAGNOSTIC TROUBLE CODES: ➢ P070500 - Transmission range sensor circuit malfunction ➢ P070512 - Transmission range sensor circuit malfunction ➢ P070514 - Transmission range sensor circuit malfunction ➢ P07051C - Transmission range sensor circuit malfunction ➢ P070600 - Transmission range sensor circuit range/performance ➢ P070661 - Transmission range sensor circuit range/performance ➢ P070696 - Transmission range sensor circuit range/performance • SYMPTOMS: ➢ Malfunction Indicator Light (MIL) illuminated ➢ 5th gear fail-safe ➢ Intermittently won’t shift into D or R ➢ Intermittently won’t shift out of Park ➢ Intermittent ly no engine cr ank/n o start in “P” or “N” with or without MIL or DTC.
23-AT-011H2023-09-06. Service bulletin. POWER TRAIN. This bulletin outlines changes to the service procedure regarding the replacement of 8-speed wet dual clutch transmissions (8WDCT) and associated transmission control unit (TCU). These changes only apply to vehicles equipped with Theta 2.5T engines. Certain transmissions (indicated by a new part number) have received an improved clutch spring. The correct TCU software update must be matched with the correct corresponding 8WDCT hardware, otherwise drivability concerns may occur.
23-AT-012H2023-09-06. Service bulletin. POWER TRAIN. This bulletin provides information related to a Transmission Control Unit (TCU) software update for certain vehicles equipped with an 8-speed wet dual clutch transmissions (8WDCT) that improves the touch point learning variation. Certain 8WDCTs (indicated by a new part number) received an improved clutch spring. The correct TCU software update must be matched with the correct corresponding 8WDCT hardware, otherwise drivability concerns may occur.
23-AT-003H-12023-09-06. Service bulletin. POWER TRAIN. If you are servicing an 8-speed vehicle with a “Check Engine” light on and one or more of the DTC listed, follow the service procedure and replace the related solenoid and harness.
23-HC-002H2023-09-06. Service bulletin. ENGINE AND ENGINE COOLING:ENGINE:ENGINE CONTROL MODULE (ECU/ECM); POWER TRAIN. This bulletin provides information related to the Engine Control Module (ECM) software update and coolant replacement for 2020-2023MY Sonata Hybrid (DN8 HEV) vehicles to improve the coolant filling mode by discharging air bubbles.
23-AT-006H-12023-09-05. Service bulletin. POWER TRAIN:AUTOMATIC TRANSMISSION; POWER TRAIN. This TSB provides information to diagnose the push button shifter operation. If you are servicing a vehicle with any symptoms listed below or DTCs (listed on Page 2) , follow the Service Procedure on Page 3. SYMPTOMS: • “Shifter System Malfunction” displayed in the cluster • Won’t shift into or out of gear or won’t shift out of Park • Incorrect gear display in cluster and/or won’t start
23-AT-009H2023-08-02. Service bulletin. POWER TRAIN; POWER TRAIN:AUTOMATIC TRANSMISSION:GEAR POSITION INDICATION (PRNDL); ENGINE AND ENGINE COOLING:ENGINE:ENGINE CONTROL MODULE (ECU/ECM); POWER TRAIN:AUTOMATIC TRANSMISSION; ELECTRICAL SYSTEM:WIRING:POSITION/LIMIT SENSOR/SWITCH. If you are servicing an 8-speed DCT front-wheel-drive vehicle with the DTC or symptoms listed below, refer to the Service Procedure to diagnose the condition. • DIAGNOSTIC TROUBLE CODES: ➢ P070500 - Transmission range sensor circuit malfunction ➢ P070512 - Transmission range sensor circuit malfunction ➢ P070514 - Transmission range sensor circuit malfunction ➢ P07051C - Transmission range sensor circuit malfunction ➢ P070600 - Transmission range sensor circuit range/performance ➢ P070661 - Transmission range sensor circuit range/performance ➢ P070696 - Transmission range sensor circuit range/performance • SYMPTOMS: ➢ Malfunction Indicator Light (MIL) illuminated ➢ 5th gear fail-safe ➢ Intermittently won’t shift into D or R ➢ Intermittently won’t shift out of P ➢ Intermittent ly no engine crank in “P” or “
23-AT-008H2023-08-02. Service bulletin. POWER TRAIN. If you are servicing an 8-speed front-wheel-drive vehicle equipped with automatic transaxle with one or more of the DTC or symptoms listed below, refer to the Service Procedure to diagnose the condition.
23-AT-002H2023-06-02. Service bulletin. POWER TRAIN. This bulletin provides service procedures to prevent possible moisture intrusion of the HP EOP (High Flow Electric Oil Pump) connector when servicing the 8-speed wet dual clutch transmission (8WDCT). If moisture enters the HF EOP connector, this can result in corrosion and insufficient connection of the terminals.
23-AT-004H2023-06-02. Service bulletin. POWER TRAIN:AUTOMATIC TRANSMISSION; POWER TRAIN. This TSB applies only if Recall 236 or Service Campaign T8N has been performed and the 8 speed wet dual clutch transmission (8WDCT) replacement is necessary related due to high pressure electric oil pump (HP EOP) DTC’s P1C2D03 (HP EOP Motor Position Sensor), P193B79 - HP EOP Performance, P0868 - Transmission Fluid Pressure (TFP) Sensor – Low. Replace the 8WDCT under this bulletin.
22-AT-011H2022-11-01. Service bulletin. POWER TRAIN. This bulletin outlines changes to the service manual regarding the replacement of 8-speed dual clutch transmissions (DCT) and associated transmission control module (TCM). Additional steps, not in the service manual, are required within GDS prior to replacing the DCT/TCM, otherwise drivability concerns and/or DTCs may occur.
22-AT-010H2022-08-24. Service bulletin. POWER TRAIN; ENGINE AND ENGINE COOLING. If you are servicing an applicable vehicle with a “Check Engine” light on and one or more of the DTC listed below, follow the Service Procedure and replace the valve body internal harness and the input/output speed sensor.
22-01-059H2022-08-24. Service bulletin. POWER TRAIN. This bulletin provides the procedure to update the TCU software to improve drivability and shift quality.
22-AT-009H2022-08-05. Service bulletin. POWER TRAIN. If you are servicing an applicable vehicle with a “Check Engine” light on and one or more of the DTC listed on Page 2, follow the repair procedure and perform the diagnosis. If necessary, replace the High Flow electric oil pump (HF EOP) for HF EOP issues or the Dual Clutch Transmission for High Pressure electric oil pump (HP EOP) issues.
22-AT-005H2022-05-10. Service bulletin. POWER TRAIN. If you are servicing an applicable vehicle with a “Check Engine” light on and one or more of the DTC listed below, follow the repair procedure and replace the related solenoid and valve body harness.

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