Mercedes-Benz bulletin LI20.40-P-078593
What it saysComplaint Engine cooling fan running for an extended time after switching off vehicle. NHTSA’s full summary ↓
Mercedes-Benz filed this with NHTSA as a service bulletin dated Nov 19, 2024, received Nov 22, 2024, about the engine. It names 33 model years (2019–2024). 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 communicationComplaint Engine cooling fan running for an extended time after switching off vehicle. Cause Optimized thermal management in latest PTCU software. Remedy This is a normal function in the latest PTCU software. Engine fan will operate for up to 20 minutes after ignition is switched off. Note: Repair work should only be performed if a clear malfunction is identified
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| LI20.40-P-078593 | Service bulletin | Nov 19, 2024 | 11010744 | PDF, 34 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: 2020 Mercedes-Benz AMG GT43; 2024 Mercedes-Benz AMG GT53E.
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 31 model years this bulletin names have filed 832 complaints with NHTSA since 2015. 201 of them name Engine — 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.
I brought my car in for routine service and was told I needed a rear main seal. I had the car inspected when I purchased it appx 13k miles ago because I saw online there was a lot of people having this issue with their vehicles. It’s a known manufacturer defect. At that time there was no issue. Now at 40k miles it began to leak.
2019 Mercedes-Benz E-Class · Engine · filed with NHTSA Jan 4, 2026 · ODI 11708627
On July 7, 2026, my 2022 Mercedes-Benz GLE 350 experienced a serious engine malfunction. After stopping at a traffic light, the engine began shaking violently and idling roughly. When the traffic light turned green, the vehicle accelerated extremely slowly and had very little power, making it difficult to clear the intersection.
2022 Mercedes-Benz GLE-Class · Engine · filed with NHTSA Jul 13, 2026 · ODI 11749953
Vehicle: 2022 Mercedes-Benz S580 The vehicle is experiencing a severe and violent drivetrain "jolt" or "push" during gear transitions, specifically when shifting from 5th to 6th gear at cruising speeds. On multiple occasions, the jolt was so forceful that passengers believed the vehicle had been rear-ended by another car.
2022 Mercedes-Benz S-Class · Engine · filed with NHTSA Apr 19, 2026 · ODI 11732269
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 engine
Source: same model, same component group57 other manufacturer communications filed against these Mercedes-Benz models under the same component group (engine), newest first. The eight newest are listed; the rest are on the Mercedes-Benz list.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| LI18.00-P-073137 | Service bulletin | Sep 26, 2026 | Complaint Sporadic warning message in instrument cluster "Engine oil pressure stop switch off vehicle" (or similar) is shown in red on vehi… |
| LI20.10-P-075374 | Service bulletin | Sep 17, 2026 | Complaint Red coolant warning in instrument cluster. Fault codes U019F00 or U019F87 current/stored in MRG1 control unit. Cause Various cause… |
| LI01.20-P-080884 | Service bulletin | Aug 12, 2026 | Complaint Oil leaks found on M176 or M177 engines diagnosed to be from the cylinder head cover area Cause Unknown (under investigation) Reme… |
| LI07.10-P-080384 | Service bulletin | Aug 7, 2026 | Complaint Customer reports Check Engine Light with possible loss of power concern. The Following DTC's are present • P210185 - The throttle… |
| NCU - 2026010004 | Service campaign | Jul 27, 2026 | • Always use the latest XENTRY Diagnosis software release with all available add-ons. • Make sure to follow the operation steps exactly as d… |
| LI20.10-P-072886 | Service bulletin | Jul 24, 2026 | Complaint Check Engine Light ON with DTC P012800 "The Coolant Temperature is Below the Specified Temperature" active and/or stored in the ME… |
| Emissions - 2024100016 | Emissions | Jul 24, 2026 | Mercedes-Benz AG (“MBAG”), the manufacturer of Mercedes-Benz, has determined that on certain MY 2019-2021 C-Class, G-Class, GLC, GT, S-Class… |
| LI07.61-P-080241 | Service bulletin | Jun 11, 2026 | Complaint CEL ON with DTC P061197 "the control unit fuel injector has a malfunction output stage fault of control unit is restricted" active… |
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 LI20.40-P-078593 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 LI20.40-P-078593 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 LI20.40-P-078593 cover?
The manufacturer filed it against 33 model years: 2024 Mercedes-Benz AMG GT, 2023 Mercedes-Benz AMG GT, 2022 Mercedes-Benz AMG GT, 2021 Mercedes-Benz AMG GT, 2020 Mercedes-Benz AMG GT, 2019 Mercedes-Benz AMG GT and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.