Mercedes-Benz bulletin LI27.60-P-079083
What it saysComplaint Harsh 1-2, 2-3, and/or 3-4 shift Jerky shifting Jolting when accelerating from stop Cause Insufficient software application causing elevated K81/K27/B05 fill time adaptations and elevated torque adaptations… NHTSA’s full summary ↓
Mercedes-Benz filed this with NHTSA as a service bulletin dated May 5, 2026, received Mar 27, 2025, about the power train — 6 documents under this number. It names 3 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 • Harsh 1-2, 2-3, and/or 3-4 shift • Jerky shifting • Jolting when accelerating from stop Cause Insufficient software application causing elevated K81/K27/B05 fill time adaptations and elevated torque adaptations for concerning shift. Note: Shift quality in E Performance models can be affected if the HV Battery state of charge (SOC) reaches 25% or below. Remedy Check VGS software level, and follow relevant remedy instructions. (see attachment) Vehicles with VGS software levels up to 22A: As of 1/28/2026, aftersales software improvement has been released for model years 2024-2025 GLC43 (A 001 902 20 34). This software has been implemented in production as of model year 2026. Please ensure your Xentry machine is up to date with the latest Add Ons and continue with the following steps: Note: ALL steps must be performed to rectify concern 1. Check for new VGS software, update if available 2. Check transmission oil level and correct, if necessary (transmission oil temperature > 60 °C) 3. Perform Xentry Valve Flushing procedure at least 3x 4. Perform resetting of deceleration values (VGS > Special Procedures > Special procedure > Resetting learned values Deceleration mode) 5. Perform a standstill adaptation, then read out new EEPROM data 6. Perform driving adaptation(s) while adhering to the below parameters for at least 20-30 miles Note: There is no menu in Xentry for this procedure. We recommend displaying the torque in the instrument cluster. If all below parameters are met at the time the shift, a driving adaptation will automatically occur. Harsh 1-2 Perform a driving adaptation of 4-5 (adapts K81 for the 1-2 shift) Harsh 2-3 Perform a driving adaptation of 6-7 (adapts B05 for the 2-3 shift) Harsh 3-4 Perform a driving adaptation of 3-4 (adapts K27 directly) - See attached PDF for min/max torque, and RPM parameters - Transmission oil temperature > 30°C (>86°F) - Level track (no incline/decline) - Slippery drive program - Display the torque in the instrument cluster - Constant engine torque - Do not shift via paddle If the vehicle returns and already had ALL steps in this LI performed on a previous visit or has software level 23A and newer: Please submit a TIPS case to the Powertraininbox and ensure the following is included: - Initial Quick Test w/ Freeze Frame Data - VGS Control Unit Log - Initial EEPROM (before any adaptations or Xentry procedures
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| LI27.60-P-079083 | Service bulletin | May 5, 2026 | 11032363 | PDF, 203 KB |
| LI27.60-P-079083 | Service bulletin | Feb 7, 2026 | 11028649 | PDF, 39 KB |
| LI27.60-P-079083 | Service bulletin | Jan 29, 2026 | 11027861 | PDF, 39 KB |
| LI27.60-P-079083 | Service bulletin | Jan 24, 2026 | 11027791 | PDF, 38 KB |
| LI27.60-P-079083 | Service bulletin | Sep 8, 2025 | 11023043 | PDF, 37 KB |
| LI27.60-P-079083 | Service bulletin | Mar 24, 2025 | 11016044 | PDF, 36 KB |
What the document itself lists
Part the bulletin names
| Part number | Description | Qty | Find it |
|---|---|---|---|
| A 001 902 20 34 | — | — |
Read by machine from the document NHTSA serves (3 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 91 complaints with NHTSA since 2015. 7 of them name 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.
Vehicle experiences a severe, abrupt jerk/jolt during deceleration around the 5th-to-4th gear downshift. The issue occurs consistently when slowing down. Dealership verified the condition on Repair Order #1906625 and confirmed a transmission flaw. Dealer stated software is required from the manufacturer with no ETA for release.
2025 Mercedes-Benz GLC-Class · Power Train · filed with NHTSA Aug 6, 2026 · ODI 11755359
While at a stop with foot on brake, the vehicle surges forward powerfully making a loud noise despite having foot on brake. Forcefully pushing on brake pedal harder eventually stops the car. Most recent time the display screen showed "Transmission Deactivated". Dealership drove car once but did not perform service inspection.
2026 Mercedes-Benz GLC-Class · Power Train · filed with NHTSA Jan 16, 2026 · ODI 11711555
While driving my 2024 Mercedes-Benz GLC 300 on California highways, the vehicle has repeatedly experienced sudden uncontrolled deceleration, unexpected transmission downshifts into 2nd gear, severe transmission jerking, and complete loss of accelerator response.
2024 Mercedes-Benz GLC-Class · Power Train · filed with NHTSA May 27, 2026 · ODI 11740380
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 LI27.60-P-079083 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 LI27.60-P-079083 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 LI27.60-P-079083 cover?
The manufacturer filed it against 3 model years: 2026 Mercedes-Benz GLC-Class, 2025 Mercedes-Benz GLC-Class, 2024 Mercedes-Benz GLC-Class. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.