Mercedes-Benz bulletin LI27.19-P-080823
Mercedes-Benz filed this with NHTSA as a service bulletin dated Aug 25, 2026, received Aug 5, 2026, about the power train — 2 documents under this number. It names 11 model years (2021–2023). 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.
What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationComplaint Customers may report one or more of the following: • Transmission malfunction message • Check engine light illuminated • Shifts into N • Concern disappears after ignition cycle When performing a quick test, the following fault code is stored in Y3/14 - Transmission control for 8-speed dual-clutch transmission (DKG): P056300 The on-board power supply voltage is too high. Cause An overvoltage condition is detected exclusively within the transmission control unit, storing fault P056300 once the measured voltage exceeds 16V. Remedy This LI applies if the freeze frame data for P056300 show a supply voltage between 15.75 to 16.50 volts, and no other control units report overvoltage. (figure 1) Long Term Resolution: Software resolutions are being rolled out for various models. Check validity and ensure your Xentry is updated with latest Addons before continuing: 1. Perform software update for Y3/14 - Transmission control for 8-speed dual-clutch transmission (DKG) - available software listed in Parts 2. Clear fault memory and perform final test drive Short Term Resolution: Please clear faults and perform an extended test drive. The vehicle may be released to the customer until software is available. If the customer complaint matches this LI and the software currently installed on the vehicle is not listed, please submit a TIPS case to the Powertrain inbox with the following information: - Initial Quick Test w/ Freeze Frame Data - DKG Control Unit Log - Latest EEPROM data - Screenshot of software availability
Documents filed under this number
| Document | Kind | Dated | NHTSA id |
|---|---|---|---|
| LI27.19-P-080823 | Service bulletin | Aug 25, 2026 | 11036514 |
| LI27.19-P-080823 | Service bulletin | Aug 4, 2026 | 11035713 |
The summary is NHTSA’s abstract of the document, as filed under 49 CFR 579.5; the full text comes from the manufacturer or a dealer. 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. Quote it 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.
Common questions
Source: NHTSA, 49 CFR 579.5Is Mercedes-Benz LI27.19-P-080823 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 LI27.19-P-080823 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 LI27.19-P-080823 cover?
The manufacturer filed it against 11 model years: 2022 Mercedes-Benz A-Class, 2021 Mercedes-Benz A-Class, 2023 Mercedes-Benz CLA-Class, 2022 Mercedes-Benz CLA-Class, 2021 Mercedes-Benz CLA-Class, 2023 Mercedes-Benz GLA-Class and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.