Mercedes-Benz bulletin LI77.21-P-080504
What it saysComplaint The panoramic sliding sunroof operates in a stepped movement. NHTSA’s full summary ↓
Mercedes-Benz filed this with NHTSA as a service bulletin dated May 18, 2026, received Apr 25, 2026, about the visibility/wiper — 2 documents under this number. It names 4 model years (2024–2026). 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 communicationComplaint The panoramic sliding sunroof operates in a stepped movement. The panoramic roof becomes denormalized without an apparent reason (not directly after control unit replacement). Automatic operation of the glass panel and roller sunblind is not possible; only tip‑mode operation is available. In combination with one, serval, or all of the following Fault Codes stored in the panoramic roof control unit (PSD, A98, N70/1, TSSR223): • B1E9157 • B1E9151 • B1E9146 • B1E7551 • B184951 • B184946 Note: For 206, please see LI77.21-P-074971 for complaints of the sliding sunroof panel of panoramic sliding sunroof reverses (temporarily, once, multiple times) during closing process without an entrapment event Cause Resetting the panoramic roof control unit (PSD, A98, N70/1, TSSR223) can lead to loss of normalization. The root cause for the control unit reset is currently under investigation. Remedy Contribution to cause analysis: • CPrint the attached document “Panoramic Roof Customer Questionnaire.” • Complete the questionnaire together with the customer. • Open a TIPS case and attach the completed questionnaire. • Submit the TIPS case to the Body / Chassis / Entertainment inbox. Remedy: Perform Initial Start‑Up of the panoramic roof control unit (PSD, A98, N70/1, TSSR223).
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| LI77.21-P-080504 | Service bulletin | May 18, 2026 | 11032874 | PDF, 40 KB |
| LI77.21-P-080504 | Service bulletin | Apr 24, 2026 | 11031557 | PDF, 40 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 themAlso filed against model years this site has no page for: 2026 Mercedes-Benz E53 E 4MATIC+ ALL-Terrain.
A 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 3 model years this bulletin names have filed 27 complaints with NHTSA since 2015. 1 of them name Visibility/Wiper — 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.
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 visibility/wiper
Source: same model, same component group9 other manufacturer communications filed against these Mercedes-Benz models under the same component group (visibility/wiper), newest first. The eight newest are listed; the rest are on the Mercedes-Benz list.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| LI83.55-P-080937 | Service bulletin | Sep 1, 2026 | Cause Internal failure of the scroll wheel within the AC compressor. Remedy Check the compressor's index and part number Figure 1 against Ta… |
| PSL-NCU Return Parts 6/19 | Other | Jun 19, 2026 | Dear Mercedes-Benz USA Dealers, The part numbers listed in the chart below should no longer be installed, and any existing stock must be ret… |
| LI82.30-P-059239 | Service bulletin | May 19, 2026 | Complaint There are several types of complaint about noises or poor windshield wiper wiping performance: A: Wiper blades squeaking, chatteri… |
| LI83.70-P-080411 | Service bulletin | Apr 13, 2026 | Complaint No heating output is available during electric driving operation. In conventional (combustion engine) driving operation, full heat… |
| LI72.40-P-071889 | Service bulletin | Apr 7, 2026 | Complaint When closing the door, the side window may remain slightly open (short stroke position). Automatic window raising function of side… |
| LI83.30-P-079850 | Service bulletin | Jan 16, 2026 | Complaint Customer states the AC either does not cool/has poor performance or heat is insufficient. Cause Many possible root causes Remedy *… |
| LI83.20-P-079559 | Service bulletin | Jul 18, 2025 | Complaint No cooling output, compressor inoperative. Cause Currently under analyzed. Remedy Please create a TIPS case and provide the follow… |
| LI83.30-P-079081 | Service bulletin | Apr 21, 2025 | Complaint Random heating of air conditioning system. Cause Temperature sensor in overhead control panel (OCP) delivering incorrect values: T… |
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for Mercedes-Benz, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is Mercedes-Benz LI77.21-P-080504 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 LI77.21-P-080504 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.
Which vehicles does LI77.21-P-080504 cover?
The manufacturer filed it against 4 model years: 2026 Mercedes-Benz E-Class, 2025 Mercedes-Benz E-Class, 2024 Mercedes-Benz E-Class, 2026 Mercedes-Benz E53 E 4MATIC+ ALL-Terrain. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.