Mercedes-Benz bulletin LI77.21-P-077779
What it saysSliding sunroof panel of panoramic sliding sunroof reversed (temporarily, once, multiple times) during closing process without entrapment event. NHTSA’s full summary ↓
Mercedes-Benz filed this with NHTSA as a service bulletin dated May 4, 2024, received May 30, 2024, about the visibility/wiper. It names 2 model years (2023–2024). 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 communicationSliding sunroof panel of panoramic sliding sunroof reversed (temporarily, once, multiple times) during closing process without entrapment event. Cause remains open. For analysis, the information from the control unit log of the panoramic roof control unit (TSSR254) is required via a TIPS case. Further analyses Requirement: • The teach-in run for the automatic reversing function of the panoramic roof via XENTRY has still NOT been carried out • SW-SNR is A254 902 9702 with parameter data set A254 903 2902 or A254 903 4802 Please perform the following steps: 1. Create a TIPS case 2. Create control unit log of panoramic roof control unit (TSSR223, A98, PSD) (prerequisite: add-on 25071) and attach to TIPS case
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| LI77.21-P-077779 | Service bulletin | May 4, 2024 | 11000544 | PDF, 39 KB |
What the document itself lists
Part the bulletin names
| Part number | Description | Qty | Find it |
|---|---|---|---|
| A254 902 9702 | — | — |
Read by machine from the document NHTSA serves (2 pages), read Sep 30, 2026. A part number is shown only where it matches Mercedes-Benz’s own catalogue shape, an operation only with its code and time, and a description only where the reader got it whole; anything it could not settle is left out, and the PDF is the record. Times are the manufacturer’s warranty allowances, not a quote. Listings and prices on eBay Motors are the seller’s.
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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 body for the 2024 GLC-Class →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 2 model years this bulletin names have filed 95 complaints with NHTSA since 2015.
The rear lift gate closes unexpectedly when standing behind the vehicle and loading or unloading the cargo area. The keyless soft close activates even though there is no foot movement, or when there is minimal movement. This happens without warning. On several occasions this has happened to me, and also to my wife.
2024 Mercedes-Benz GLC-Class · Structure · filed with NHTSA Jul 8, 2026 · ODI 11749171
The rear door randomly closes with force unexpectantly. We contacted the Mercedes dealer where the car was purchased and is serviced. They responded it can not be fixed and was an ongoing concern of many owners
2023 Mercedes-Benz GLC-Class · Structure · filed with NHTSA Jun 3, 2025 · ODI 11664589
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 the Mercedes-Benz GLC-Class 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 |
|---|---|---|---|
| LI83.90-P-080935 | Service bulletin | Sep 25, 2026 | Complaint CEL illuminates and/or AC does not blow cold. Cause Potentially relevance to hardware and/or software Remedy Scenario 1: 1. If the… |
| 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… |
| 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 *… |
| LI83.30-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… |
| LI77.21-P-075807 | Service bulletin | Jan 23, 2025 | Complaint Sliding sunroof panel of panoramic sliding sunroof reverses (temporarily, once, multiple times) during closing process without ent… |
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-077779 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-077779 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 Mercedes-Benz warranty extension on file lists the ones Mercedes-Benz has filed.
Which vehicles does LI77.21-P-077779 cover?
The manufacturer filed it against 2 model years: 2024 Mercedes-Benz GLC-Class, 2023 Mercedes-Benz GLC-Class. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.