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Federal filingsHome›Bulletins›Mercedes-Benz› LI20.10-P-072886
Manufacturer communication · Service bulletin

Mercedes-Benz bulletin LI20.10-P-072886

What it saysComplaint Check Engine Light ON with DTC P012800 "The Coolant Temperature is Below the Specified Temperature" active and/or stored in the ME (N3/10). NHTSA’s full summary ↓

Mercedes-Benz filed this with NHTSA as a service bulletin dated Jul 24, 2026, received Jun 7, 2021, about the engine — 6 documents under this number. It names 97 model years (2016–2026). 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 communication

Complaint Check Engine Light ON with DTC P012800 "The Coolant Temperature is Below the Specified Temperature" active and/or stored in the ME (N3/10). There are no drivability concerns related to this complaint. Cause Root cause varies Remedy Prior to performing any repairs for this complaint: With a cold engine, pressurize the high temp coolant circuit and while it's under pressure, release the cap on the low temp coolant circuit and check if the pressure drops right away or not. If the pressure drops, the lower coolant hoses are swapped. Correct this, fill, bleed and test drive the vehicle. If the complaint returns, then continue with the steps below. IMPORTANT: Use VMI to check for the following emission extended warranty –> Engine Thermostat (incl. software update) MY19-23, Various Models and Platforms (167, 190, 205, 213, 217, 222, 223, 232, 253, 290, 463) If the vehicle is covered under the above emission extended warranty, please perform steps outlined in the accompanying NCU prior to those outlined in this document. If vehicle is not covered under the above emission extended warranty or the complaint continues to occur, then proceed as follows: Check for available software updates to the ME (N3/10). If updated software is available, perform the update, clear the DTC and the perform each of the "WARM START" and "COLD START" test drives listed below twice. If the code does not re-appear then release the vehicle. If there is no new software available OR the DTC returns after the test drives then perform the following steps: • Drain the coolant through a fine mesh sieve and check for signs of debris. Additionally, inspect the coolant reservoir for debris. If any debris is found take pictures of the reservoir and the mesh filter and "flush" the system at least 2-3 times to clear as much of the debris as possible • Replace the thermostat and bleed the system as outlined in AR20.00-P-1142-04A, evacuate the system for 20-30 minutes instead of the 5 minutes specified in step 22 • NOTE: Please use all the tools specified in the AR document. The DTC will continue to populate if the circuit is not properly bled • NOTE: There are two valid thermostats to choose from in the parts section of this LI. Please verify which PN is applicable for the vehicle being worked on via XENTRY Parts Information • After bleeding the system clear the DTC and perform each of the "WAR

Kind Service bulletin Manufacturer date Jul 24, 2026 Received by NHTSA Jun 7, 2021 Components Engine, Electrical System, Equipment Adaptive/Mobility First dated Apr 20, 2021

Documents filed under this number

DocumentKindDatedNHTSA idAt NHTSA
LI20.10-P-072886Service bulletinJul 24, 202611035234PDF, 41 KB
LI20.10-P-072886Service bulletinApr 21, 202611031581PDF, 41 KB
LI20.10-P-072886Service bulletinFeb 11, 202611028810PDF, 38 KB
LI20.10-P-072886Service bulletinJan 6, 202611027120PDF, 38 KB
LI20.10-P-072886Service bulletinAug 16, 202210219259PDF, 41 KB
LI20.10-P-072886Service bulletinApr 20, 202110195221not found

What the document itself lists

Parts the bulletin names

Part numberDescriptionQtyFind it
A1772007901THERMOSTAT 1 M177LS2, M177LSE X—eBay Motors →
A1772008801THERMOSTAT 1 M176, M177LS1, M178 X—eBay Motors →

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.

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.

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 cooling system for the 2026 AMG GT →

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 them

and 44 more on this site: 2023 Mercedes-Benz GLC-Class, 2022 Mercedes-Benz GLC-Class, 2021 Mercedes-Benz GLC-Class, 2020 Mercedes-Benz GLC-Class, 2019 Mercedes-Benz GLC-Class, 2018 Mercedes-Benz GLC-Class, 2026 Mercedes-Benz GLE-Class, 2025 Mercedes-Benz GLE-Class, 2024 Mercedes-Benz GLE-Class, 2023 Mercedes-Benz GLE-Class, 2022 Mercedes-Benz GLE-Class, 2021 Mercedes-Benz GLE-Class, 2020 Mercedes-Benz GLE-Class, 2019 Mercedes-Benz GLE-Class, 2018 Mercedes-Benz GLE-Class, 2017 Mercedes-Benz GLE-Class, 2026 Mercedes-Benz GLS-Class, 2025 Mercedes-Benz GLS-Class, 2024 Mercedes-Benz GLS-Class, 2023 Mercedes-Benz GLS-Class, 2022 Mercedes-Benz GLS-Class, 2021 Mercedes-Benz GLS-Class, 2020 Mercedes-Benz GLS-Class, 2019 Mercedes-Benz GLS-Class, 2018 Mercedes-Benz GLS-Class, 2017 Mercedes-Benz GLS-Class, 2026 Mercedes-Benz S-Class, 2025 Mercedes-Benz S-Class, 2024 Mercedes-Benz S-Class, 2023 Mercedes-Benz S-Class, 2022 Mercedes-Benz S-Class, 2021 Mercedes-Benz S-Class, 2020 Mercedes-Benz S-Class, 2019 Mercedes-Benz S-Class, 2018 Mercedes-Benz S-Class, 2017 Mercedes-Benz S-Class, 2026 Mercedes-Benz SL-Class, 2025 Mercedes-Benz SL-Class, 2024 Mercedes-Benz SL-Class, 2023 Mercedes-Benz SL-Class, 2022 Mercedes-Benz SL-Class, 2020 Mercedes-Benz SL-Class, 2019 Mercedes-Benz SL-Class, 2018 Mercedes-Benz SL-Class.

Also filed against model years this site has no page for: 2022 Mercedes-Benz AMG C63 S; 2022 Mercedes-Benz AMG E63; 2022 Mercedes-Benz AMG E63S; 2020 Mercedes-Benz AMG GT S; 2022 Mercedes-Benz AMG GT63; 2022 Mercedes-Benz AMG GT63 S; 2024 Mercedes-Benz AMG GT63 S E; 2024 Mercedes-Benz AMG GT63 S E Performance; 2026 Mercedes-Benz AMG GT63 S E Performance 4MATIC+; 2023 Mercedes-Benz AMG S 63 E 4MATIC+; 2024 Mercedes-Benz AMG S 63 E 4MATIC+; 2026 Mercedes-Benz AMG S 63 E 4MATIC+; 2024 Mercedes-Benz AMG SL63 S E.

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 database

Owners of the 84 model years this bulletin names have filed 2,830 complaints with NHTSA since 2015. 1,244 of them name Engine, Electrical System — 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.

On the 2020 Mercedes-Benz GLE-Class, the 13 owners who gave an odometer reading for Electrical System reported it at a median of 6,615 miles. That figure is one model year’s, not the whole range this bulletin covers — medians from different model years are not averaged.

My mom and I were in her car brand new Mercedes adaptive cruise was on the car started to act up with all the warning lights again, which shut all safety systems down air back seatbelts, adaptive cruise, Tronics and the engine wall between 18 wheeler and the freeway wall slammed the vehicle into the freeway hall causing about $5000 worth…

2023 Mercedes-Benz SL-Class · Electrical System · filed with NHTSA Jan 21, 2025 · ODI 11637467

As I was driving down road car began to lose power, check engine light came on and car went into limp mode. Car was towed to nearest repair shop where analysis was made. I was advised to take to dealership for repair. Advised that there was a service campaign issued by the manufacturer on GLB class with M260 motors. See attached report.

2021 Mercedes-Benz GLB-Class · Engine · filed with NHTSA Jul 30, 2026 · ODI 11753817

Complete engine failure mid driving on highway. NO engine light prior to complete engine failure. Vehicle has been towed to two different Mercedes Benz auto dealerships. Both service directors concur that this should not have occurred with zero warning and low mileage of 64,856 with an impeccable service record at Mercedes Benz Came on…

2020 Mercedes-Benz GLB-Class · Engine · filed with NHTSA Aug 15, 2026 · ODI 11757113

In depth: 2017 Mercedes-Benz C-Class engine problems → · 2016 Mercedes-Benz C-Class engine problems →

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 group

87 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.

NumberKindDatedNHTSA’s summary
LI18.00-P-073137Service bulletinSep 26, 2026Complaint Sporadic warning message in instrument cluster "Engine oil pressure stop switch off vehicle" (or similar) is shown in red on vehi…
LI20.10-P-075374Service bulletinSep 17, 2026Complaint Red coolant warning in instrument cluster. Fault codes U019F00 or U019F87 current/stored in MRG1 control unit. Cause Various cause…
PSL-NCU Return Parts 8/14OtherAug 15, 2026Dear Mercedes-Benz USA Dealers, The part numbers listed in the chart below should no longer be installed, and any existing stock must be ret…
LI01.20-P-080884Service bulletinAug 12, 2026Complaint 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-080384Service bulletinAug 7, 2026Complaint Customer reports Check Engine Light with possible loss of power concern. The Following DTC's are present • P210185 - The throttle…
NCU - 2026010004Service campaignJul 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…
Emissions - 2024100016EmissionsJul 24, 2026Mercedes-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-080241Service bulletinJun 11, 2026Complaint 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.

Photo: Christian Buehner / Unsplash

Common questions

Source: NHTSA, 49 CFR 579.5

Is Mercedes-Benz LI20.10-P-072886 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 LI20.10-P-072886 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 LI20.10-P-072886 cover?

The manufacturer filed it against 97 model years: 2026 Mercedes-Benz AMG GT, 2025 Mercedes-Benz AMG GT, 2024 Mercedes-Benz AMG GT, 2023 Mercedes-Benz AMG GT, 2021 Mercedes-Benz AMG GT, 2020 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.