Hyundai bulletin 23-HC-002H
What it saysThis 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… NHTSA’s full summary ↓
Hyundai filed this with NHTSA as a service bulletin dated Aug 25, 2023, received Sep 6, 2023, about the power train. It names 4 model years (2020–2023). A service bulletin is not a safety recall: it is the manufacturer telling its dealers how to diagnose or repair a condition, and whether the work is paid for depends on the warranty in force. Quoting the number at a service desk can save a diagnosis.
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What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationThis 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.
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| 23-HC-002H | Service bulletin | Aug 25, 2023 | 10241883 | PDF, 1,527 KB |
The summary is NHTSA’s abstract of the document, as filed under 49 CFR 579.5. One communication is usually filed as several documents — the bulletin, a dealer notice, an owner letter — and the number on any of them finds this page. A PDF link is shown only once NHTSA’s own server has been seen to serve that document; the rest are checked over the following nights. Quote the number at a service desk; it is what the dealer’s system is keyed on.
Doing the repair yourself, or pricing it before the shop does? Search the part by fitment on eBay Motors — the listing and the price are the seller’s.
Find the engine control module (ecu/ecm) for the 2023 Sonata →Affiliate disclosure: some links on this page are affiliate links. If you request a quote or buy through them we may earn a commission at no extra cost to you. Nothing on this page changes because of it.
Model years it names
Source: as the manufacturer filed themA vehicle page’s bulletin list shows the newest few communications filed against that model year; the count there is every one.
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What owners reported
Source: NHTSA complaint databaseOwners of the 4 model years this bulletin names have filed 605 complaints with NHTSA since 2015. 262 of them name Engine, Power Train — the same broad component group this bulletin is filed under. NHTSA groups complaints coarsely, so that means the same area of the vehicle, not necessarily the same fault.
Occasionally there is a serious delay when trying to accelerate. Car tends to jerk/buck when accelerating, usually in the lower gears. I have no idea if this is a transmission issue or a fuel injection issue, but my dealership has not been able to detect an issue and keeps telling me everything is normal when it clearly isn't.
2020 Hyundai Sonata · Power Train · filed with NHTSA Jan 4, 2021 · ODI 11386446
Initially had loss of cabin heat. Later, vehicle randomly overheated. Repair shop replaced EGR due to finding confidant buildup of water/coolant mix. Within one week, problem returned. Dealer notified me that while replacing another part they found a TSB for coolant leakage into exhaust that was consistent with my issue.
2021 Hyundai Sonata · Engine · filed with NHTSA Feb 13, 2024 · ODI 11571605
The contact owns a 2022 Hyundai Sonata. The contact stated while driving 30 MPH, there was a delay while shifting into another gear. The contact stated that the chassis warning light was illuminated. The contact also stated that the front driver’s side door failed to latch and close properly.
2022 Hyundai Sonata · Power Train · filed with NHTSA Jul 24, 2023 · ODI 11534058
In depth: 2021 Hyundai Sonata engine problems →
A complaint is one owner’s account, not a defect finding, and a bulletin is not a recall. Nothing here says this bulletin was issued because of these complaints, or that the repair it describes fixed them. Complaint files on this site begin in 2015.
More bulletins about the power train
Source: same model, same component group15 other manufacturer communications filed against the Hyundai Sonata under the same component group (power train), newest first. The eight newest are listed; the rest are on the Hyundai list.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| LA15 | Warranty extension | Jul 27, 2026 | Certain Sonata (DN8) vehicles may exhibit a transmission oil leak at the bottom of the valve body cover due to a loose oil level plug that c… |
| 26-AT-005H | Service bulletin | Jun 5, 2026 | This bulletin provides information related to a Transmission Control Unit (TCU) software update for some vehicles equipped with an 8-speed w… |
| 26-AT-001H | Service bulletin | Mar 3, 2026 | Some Santa Cruz (NXT), Santa Fe (TMA, MX5A), and Sonata (DN8A) models may require replacement of the 8-speed wet dual clutch transmission… |
| 25-AT-001H | Service bulletin | May 30, 2025 | Certain Santa Fe (TMA) and Sonata (DN8/DN8A) vehicles equipped with 8-speed dual clutch transmissions (8DCT) may exhibit one of the DTCs lis… |
| 24-AT-001H-1 | Service bulletin | Dec 18, 2024 | This bulletin provides the procedure for updating the automatic transmission TCU (Transmission Control Unit) software to improve shift quali… |
| 24-AT-002H | Service bulletin | Apr 9, 2024 | This TSB provides a procedure to diagnose and replace, if necessary, an automatic transmission with Incorrect Ratio DTC… |
| 24-AT-001H | Service bulletin | Feb 28, 2024 | This bulletin provides the procedure for updating the automatic transmission TCU and ECU software (Santa Fe ONLY) to improve shift quality… |
| 23-AT-006H-2 | Service bulletin | Nov 10, 2023 | This TSB provides information to diagnose the push button shifter operation. |
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for Hyundai, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is Hyundai 23-HC-002H a recall?
No. A service bulletin is a manufacturer communication filed with NHTSA under 49 CFR 579.5; a safety recall carries an NHTSA campaign number (two digits, a letter, six digits) and a federal duty to repair for free. Check the vehicle’s recalls by VIN at nhtsa.gov/recalls, or on its page here.
Is the 23-HC-002H repair free?
Not automatically. A service bulletin describes how to diagnose or repair a condition; who pays depends on the warranty in force, any extension, and the dealer. Quoting the number can save a diagnosis either way. Every Hyundai warranty extension on file lists the ones Hyundai has filed.
Which vehicles does 23-HC-002H cover?
The manufacturer filed it against 4 model years: 2023 Hyundai Sonata, 2022 Hyundai Sonata, 2021 Hyundai Sonata, 2020 Hyundai Sonata. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.