Hyundai service campaign 9B4
What it saysCertain Elantra Hybrid (CN7 HEV), Sonata Hybrid (DN8 HEV), and Tucson Hybrid (NX4 HEV) vehicles may exhibit a warning light due to DTC Code P1BB20 (12V Lithium Battery Cell Voltage High). NHTSA’s full summary ↓
Hyundai filed this with NHTSA as a service campaign dated Aug 21, 2025, received Feb 17, 2025, about the electrical system — 5 documents under this number: 25-01-010H-1 9B4 OL, 25-01-010H-1 DN, 25-01-010H-1 TSB, 25-01-010H DN and 1 more. It names 9 model years (2020–2024). A service campaign is not a safety recall — there is no NHTSA campaign number and no federal requirement — but it is usually work the manufacturer pays for on the vehicles it names; the dealer checks the VIN against the manufacturer’s list.
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What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationWhat it applies to, as the document itself states it — the build window in the manufacturer’s own words, read by machine from the PDF NHTSA serves. The build date is on the certification label in the driver’s door jamb; the dealer settles a borderline vehicle by its VIN.
Certain Elantra Hybrid (CN7 HEV), Sonata Hybrid (DN8 HEV), and Tucson Hybrid (NX4 HEV) vehicles may exhibit a warning light due to DTC Code P1BB20 (12V Lithium Battery Cell Voltage High). The California Air Resources Board has determined that these vehicles may be releasing air pollutants which exceed Federal and California standards.
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| 25-01-010H-1 9B4 OL | Service campaign | Aug 21, 2025 | 11022097 | PDF, 228 KB |
| 25-01-010H-1 DN | Service campaign | Jul 16, 2025 | 11020799 | PDF, 599 KB |
| 25-01-010H-1 TSB | Service campaign | Jul 16, 2025 | 11020798 | PDF, 802 KB |
| 25-01-010H DN | Service bulletin | Feb 11, 2025 | 11014286 | PDF, 232 KB |
| 25-01-010H TSB | Service campaign | Feb 11, 2025 | 11014285 | PDF, 413 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.
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 9 model years this bulletin names have filed 1,836 complaints with NHTSA since 2015. 709 of them name Electrical System, Fuel/Propulsion System — 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.
On the 2022 Hyundai Tucson, the 13 owners who gave an odometer reading for Electrical System reported it at a median of 25,800 miles. That figure is one model year’s, not the whole range this bulletin covers — medians from different model years are not averaged.
Over the last 3 months at least a dozen times the 12v auxiliary battery is completely dead after parking the car outdoors for an hour or so. This poses a safety issue, especially at night because you cannot easily access the car. You have to fumble around trying to get the key hole cover off in order to use the key supplied in the fob.
2020 Hyundai Sonata · Electrical System · filed with NHTSA Oct 1, 2024 · ODI 11617570
Fuel injector failed. The vehicle stall and accelerate poorly due to misfires. It is leaching gasoline into the oil which can result in total engine failure. Dealership verified the injector was bad. There was a warning light at one time after refueling, presumed it was my fuel cap, tightened it, and the light went away
2022 Hyundai Sonata · Fuel/Propulsion System · filed with NHTSA Sep 5, 2025 · ODI 11685272
Three incidents of shifting from park to drive or reverse and car does not move in the drive or reverse. Turning PHEV car off seems to reset it. Third time car had a high pitch whine and trying to move in reverse caused a strong shudder and check engine light to come on. Diagnostic code for power train P072200.
2022 Hyundai Tucson · Electrical System · filed with NHTSA Jan 13, 2023 · ODI 11501658
In depth: 2020 Hyundai Sonata fuel system problems → · 2022 Hyundai Tucson electrical 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 electrical system
Source: same model, same component group62 other manufacturer communications filed against these Hyundai models under the same component group (electrical system), newest first. The eight newest are listed; the rest are on the Hyundai list.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| P38 | Service bulletin | Oct 29, 2026 | Certain Tucson (NX4, NX4A), Tucson Hybrid (NX4 HEV), and Tucson Plug-in Hybrid (NX4 PHEV) vehicles may be eligible for the installation of t… |
| 26-GI-003H | Service bulletin | Oct 27, 2026 | This bulletin provides information related to the navigation and head unit software changes introduced in the 2026 2nd Navigation Map and So… |
| 26-EM-014H | Service bulletin | Sep 16, 2026 | Some Tucson (TL) vehicles equipped with a 2.0L engine may exhibit a continued DTC P132600 after an ECM logic update has been performed per T… |
| 26-BE-025H | Service bulletin | Aug 21, 2026 | Some Tucson (NX4, NX4A, NX4M), Tucson Hybrid (NX4 HEV), and Tucson Plug-In Hybrid (NX4 PHEV) vehicles may exhibit a 12-volt battery drain du… |
| LA29 / LA30 | Warranty extension | Jul 14, 2026 | Certain 2024-2026MY Sonata (DN8) and 2024-2026MY Sonata Hybrid (DN8 HEV) vehicles may exhibit intermittent battery discharge condition due t… |
| LA30 | Warranty extension | Jul 13, 2026 | Certain Sonata Hybrid (DN8 HEV) vehicles may exhibit intermittent battery discharge conditions due to the air conditioning controller not fu… |
| LA29 | Warranty extension | Jul 13, 2026 | Certain Sonata (DN8) vehicles may exhibit intermittent battery discharge condition due to the air conditioning controller not fully powering… |
| 26-EE-007H | Service bulletin | Jun 17, 2026 | Some Palisade (LX2), Tucson (NX4), and Tucson Hybrid (NX4 HEV) vehicles may experience battery drain due to continuous operation of the cool… |
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 9B4 a recall?
No. A service campaign 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 9B4 repair free?
A service campaign is usually paid by the manufacturer on the vehicles it names, within the terms and time limit the document sets; the dealer checks the VIN against the manufacturer’s list.
Which vehicles does 9B4 cover?
The manufacturer filed it against 9 model years: 2023 Hyundai Elantra, 2022 Hyundai Elantra, 2021 Hyundai Elantra, 2022 Hyundai Sonata, 2021 Hyundai Sonata, 2020 Hyundai Sonata and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone. The document itself sets the build window: built 15 Dec 2020 – 13 Feb 2023; built 29 Jan 2020 – 8 Mar 2022; built 20 Jan 2021 – 18 Dec 2023 — the build date is on the certification label in the driver’s door jamb.