Mercedes-Benz bulletin LI54.18-P-078334
What it saysComplaint The cable duct of the high-voltage drive line wiring harness is unhooked from the holder and makes contact with the transmission crossbeam. NHTSA’s full summary ↓
Mercedes-Benz filed this with NHTSA as a service bulletin dated Dec 9, 2024, received Sep 11, 2024, about the power train — 2 documents under this number. It names 3 model years (2018–2020). 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 cable duct of the high-voltage drive line wiring harness is unhooked from the holder and makes contact with the transmission crossbeam. This may cause noises (clattering/vibrating) at the underbody. Cause Due to insufficient holding ability of the catch tab at the underbody cable duct, the cable duct may become unhooked. Remedy Perform a visual check of the cable duct and the attachment point. Apply a high-temperature cable tie (see remedy and parts).
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| LI54.18-P-078334 | Service bulletin | Dec 9, 2024 | 11011764 | PDF, 38 KB |
| LI54.18-P-078334 | Service bulletin | Sep 4, 2024 | 11007674 | PDF, 37 KB |
What the document itself lists
Part the bulletin names
| Part number | Description | Qty | Find it |
|---|---|---|---|
| A 000 995 29 94 | high-temperature plastic | — | eBay Motors → |
Labour operation and the time the manufacturer allows
| Operation | Description | Time |
|---|---|---|
| 547104 | — | 0.5 hrs |
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.
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 3 model years this bulletin names have filed 250 complaints with NHTSA since 2015. 60 of them name Electrical System, 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.
The contact owns a 2019 Mercedes-Benz GLC300. The contact stated while driving 90 MPH, he received a message displaying "Key Fob not Detected," and the vehicle suddenly lost motive power. The contact was able to pull to the shoulder of the roadway, where the vehicle failed to restart. No warning lights were illuminated.
2019 Mercedes-Benz GLC-Class · Electrical System · filed with NHTSA Oct 13, 2023 · ODI 11549819
On May 14, 2023, with a little over 44,000 well-kept miles and under normal driving conditions, my 2018 GLC43 AMG blew smoke out the rear and soon after presented pooling oil under the transmission/engine area.
2018 Mercedes-Benz GLC-Class · Power Train · filed with NHTSA Jun 16, 2023 · ODI 11527446
Center COMAND screen malfunctions. No rear camera view when reversing when screen does not work. Dealer attempted a repair but issue remains. Parts ordered for replacement
2020 Mercedes-Benz GLC-Class · Electrical System · filed with NHTSA Apr 4, 2024 · ODI 11581247
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 group25 other manufacturer communications filed against the Mercedes-Benz GLC-Class under the same component group (power train), newest first. The eight newest are listed; the rest are on the Mercedes-Benz list.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| LI27.00-P-073124 | Service bulletin | Sep 26, 2026 | Complaint Customer complaints relating to automatic transmission 725.0 (NAG3 Classic /9G‑TRONIC automatic transmission) and 725.1… |
| LI35.31-P-080353 | Service bulletin | Sep 14, 2026 | Complaint Whining / humming noises (described as foghorn‑like) from the drivetrain in the rear axle area during cornering. (figure 1) On the… |
| LI27.10-P-075869 | Service bulletin | Sep 14, 2026 | Complaint Only vehicles with a variable transfer case are affected. This can be identified through control unit N45 or N15/7 in the quick te… |
| LI 27.10-P-080851 | Service bulletin | Aug 29, 2026 | Complaint Intermittent shift feel or thud/clunk noise perceived, such as a brief jerk or transmission reaction during certain driving situat… |
| LI27.00-P-075630 | Service bulletin | Aug 5, 2026 | Complaint This document is intended as a pre-case diagnostic reference for transmission related concerns. It will also ensure that if a case… |
| LI27.00-P-080840 | Service bulletin | Aug 4, 2026 | Complaint Mercedes-Benz USA is currently experiencing limited availability of transmission fluid specification ATF 236.17 due to a global su… |
| LI33.30-P-080490 | Service bulletin | Aug 3, 2026 | Complaint Leakage/oil leakage at drive pinion sealing ring (input shaft) (Figures 1-2) Minor leakage/slight seepage at coupling flange nut a… |
| LI35.30-P-058566 | Service bulletin | Jul 14, 2026 | Complaint Single throttle lift-off clunking noise from the side shaft when moving off (audible at the outboard end). The noise is heard once… |
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 LI54.18-P-078334 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 LI54.18-P-078334 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 LI54.18-P-078334 cover?
The manufacturer filed it against 3 model years: 2020 Mercedes-Benz GLC-Class, 2019 Mercedes-Benz GLC-Class, 2018 Mercedes-Benz GLC-Class. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.