# Service bulletin 21\-AT\-001H

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.

- Type: Service bulletin
- NHTSA id: 10186820
- Published by NHTSA: 2021\-02\-06
- Manufacturer's number: 21\-AT\-001H
- Manufacturer's date: 2021\-01\-14
- NHTSA component: POWER TRAIN

## NHTSA's summary

This bulletin provides the procedure to update the TCU for a rough idle in Drive with Neutral Control enabled. The rough idle may occur only at a stop in Drive with the A/C off and the ATF temperature between 158\~210°F \(70\~99°C\). This update also reduces vibration when the brake is released during Neutral Control operation and the accelerator pedal is depressed.

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2021/MC-10186820-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2021/MC-10186820-9999.pdf)

The document is the manufacturer's. This site does not hold it.

## Components

Transmission and driveline

## Vehicles listed

- 2018 to 2019 HYUNDAI SONATA

## Recalls for the same vehicles and component

- [2018135](/recalls/tc/2018135.md), 2018-03-16: Powertrain

## Other bulletins for the same vehicles and component

- [24\-AT\-002H](/bulletins/10253275.md), 2024-04-16, 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.
- [23\-AT\-003H\-1](/bulletins/10241885.md), 2023-09-06, 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\-01\-014H\-5](/bulletins/10241874.md), 2023-09-06, Service bulletin: ELECTRICAL SYSTEM; POWER TRAIN. Hyundai has launched an anti\-theft software upgrade and window decal campaign \(Campaign 993\), combined with an anti\-theft steering wheel lock campaign \(Campaign P32\), in response to an increase in thefts of certain 2011\-2022MY Hyundai vehicles not equipped with engine immobilizers targeted through social media. For certain vehicles that cannot be updated with the software \(Campaign 993\), Hyundai is offering customers steering wheel locks at the dealer \(Campaign P32\). This Dealer Best Practices Guide provides information to assist dealership personnel with customer questions relating to the immobilizer software upgrade, window decals and steering wheel lock ant\-theft solutions available from HMA through Hyundai dealers.
- [22\-AT\-007H](/bulletins/10213721.md), 2022-06-10, Service bulletin: POWER TRAIN; EQUIPMENT. Certain vehicles \(listed below\) equipped with 7\-speed Double Clutch Transmissions \(DCT\) may exhibit abnormal vibration at low speeds. This bulletin outlines the procedures for diagnosing clutch judder, updating the Transmission Control Unit \(TCU\) with revised logic, and/or replacing the Double Clutch.
- [22\-AT\-006H](/bulletins/10213720.md), 2022-06-10, Service bulletin: ENGINE AND ENGINE COOLING:ENGINE:ENGINE CONTROL MODULE \(ECU/ECM\); 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 input/output speed sensor and harness.
- [22\-AT\-005H](/bulletins/10211671.md), 2022-05-10, 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.
- [21\-AT\-014H](/bulletins/10201469.md), 2021-09-17, Service bulletin: POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE:SOFTWARE; POWER TRAIN. Certain vehicles \(listed below\) equipped with 7\-speed Double Clutch Transmissions \(DCT\) may exhibit abnormal vibration at low speeds. This bulletin outlines the procedures for diagnosing clutch judder, updating the Transmission Control Unit \(TCU\) with revised logic, and/or replacing the Double Clutch.
- [20\-AT\-005H\-1](/bulletins/10182314.md), 2020-11-06, 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.
- [20\-AT\-020H](/bulletins/10180977.md), 2020-10-08, Service bulletin: POWER TRAIN. This bulletin provides a procedure to transfer pressure data to the TCU using GDS Mobile. This procedure is necessary to reduce the transmission learning time and improve the shift quality.
- [20\-AT\-019H](/bulletins/10176196.md), 2020-06-06, Service bulletin: POWER TRAIN. If you are servicing any of the vehicles listed below with a harsh and/or delayed shift, use the GDS as shown in the Service Procedure to measure shift engagement time.

JSON: [/v1/bulletins/10186820](/v1/bulletins/10186820)

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