Mercedes-Benz bulletin LI83.20-P-051802
What it saysComplaint Vehicle with atypical reduced heat output. NHTSA’s full summary ↓
Mercedes-Benz filed this with NHTSA as a service bulletin dated Apr 1, 2025, received Apr 15, 2025, about the engine. It names 14 model years (2016–2020). 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 Vehicle with atypical reduced heat output. Cause Silicate granulate may have escaped from a damaged bag in the expansion reservoir (not visible), reducing the coolant flow in the heater heat exchanger (see picture). Remedy With the aforementioned complaint, make sure that the cooling circuit is inspected for silicate residues after all standard tests are completed. The silicate residues tend to accumulate upstream of the shutoff valve for the heater hot water pulsed valve. If there are silicate residues in the coolant, the engine must be flushed thoroughly. To make sure that all silicate residues are removed from the cooling circuit, the following parts must also be replaced (cleaning of these components is not sufficient): Coolant expansion reservoir, radiator, oil/water heat exchanger (oil cooler), heater valve, heat exchanger of heater, coolant and, if installed, the electric water pump for the residual heat utilization system. Determine the parts for the respective vehicle in the EPC.
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| LI83.20-P-051802 | Service bulletin | Apr 1, 2025 | 11017039 | PDF, 141 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: 2017 Mercedes-Benz SLK 350.
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 13 model years this bulletin names have filed 537 complaints with NHTSA since 2015. 64 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.
Multiple engine ignition coils have failed on this low mileage vehicle. History of failures are as followed. 1/18/2022 Mileage 39,246 Ignition Coil #4 6/16/2022 Mileage 40,915 Ignition Coil #2 3/16/2023 Mileage 43,866 Ignition Coil #6 and #2 4/23/2023 Mileage 44,275 Ignition Coil #1 1/15/2025 Mileage 51,560 Ignition Coil #4 Mercedes Benz…
2016 Mercedes-Benz GLE-Class · Engine · filed with NHTSA Jan 18, 2025 · ODI 11636782
The check engine light is on in my 2019 SLC (only 42K miles) and the car is emitting a lot of smoke from the exhaust pipe and it is hesitating while driving it. I almost got rear ended. I took it to the dealership and the fault code comes back as: P052E71 - The valve crankcase ventilation has a malfunction. The actuator is blocked.
2019 Mercedes-Benz SLC-Class · Engine · filed with NHTSA Apr 1, 2025 · ODI 11652173
The P06DA00 code in Mercedes-Benz vehicles is a common issue involving the oil pump solenoid, often caused by a faulty wiring harness. If this is caused by faulty wiring harness then this should be a recall since it is common and happens to all vehicles like mine. I have been told that this needs to be a recall.
2019 Mercedes-Benz GLE-Class · Engine · filed with NHTSA Apr 10, 2026 · ODI 11730457
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 group44 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… |
| LI01.30-P-072328 | Service bulletin | Mar 27, 2026 | Complaint -Check engine light illuminated. -Engine runs rough. -Poor shifting or jerking when accelerating. -Fault codes stored related to m… |
| CL - EW M157 | Other | Mar 27, 2026 | Dear Mercedes-Benz Owner: In our continuing efforts to ensure the proper performance of Mercedes-Benz products and to enhance the satisfacti… |
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 LI83.20-P-051802 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 LI83.20-P-051802 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 LI83.20-P-051802 cover?
The manufacturer filed it against 14 model years: 2016 Mercedes-Benz CLS-Class, 2017 Mercedes-Benz E-Class, 2016 Mercedes-Benz E-Class, 2019 Mercedes-Benz GLE-Class, 2018 Mercedes-Benz GLE-Class, 2017 Mercedes-Benz GLE-Class and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.