Mercedes-Benz bulletin NCU - 2023070021
What it saysMercedes-Benz AG (MBAG), the manufacturer of Mercedes-Benz vehicles, has determined that the software for the engine control unit in the subject vehicles may not meet current specifications. NHTSA’s full summary ↓
Mercedes-Benz filed this with NHTSA as a service bulletin dated Oct 9, 2023, received Nov 3, 2023, about the engine. It names 2 model years (2019–2020). 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 communicationMercedes-Benz AG (MBAG), the manufacturer of Mercedes-Benz vehicles, has determined that the software for the engine control unit in the subject vehicles may not meet current specifications. Any catalytic converter aging might not be immediately detected and therefore, the check engine Malfunction Indicator Lamp (MIL) may not illuminate as required. After a cold start in the "catalytic converter heating" operating mode, misfires might occur, and the check engine MIL would be illuminated. Consequently, these issues may not meet regulatory requirements for on-board diagnostics and/or exhaust gas emissions MBUSA will conduct a voluntary Emissions Recall Campaign in which an authorized Mercedes-Benz dealer will update the software in the affected vehicles.
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| NCU - 2023070021 | Service bulletin | Oct 9, 2023 | 10244773 | PDF, 495 KB |
What the document itself lists
The manufacturer titles it “Emissions Recall Campaign”.
Parts the bulletin names
| Part number | Description | Qty | Find it |
|---|---|---|---|
| A 000 584 54 13 | — | — | |
| A 000 584 42 14 | Sheet (CA Dealers Only) | — | eBay Motors → |
Read by machine from the document NHTSA serves (5 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 catalytic convertor for the 2020 G-Class →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 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 2 model years this bulletin names have filed 8 complaints with NHTSA since 2015. 3 of them name Electrical System, 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.
On this vehicle the oil pump-oil control valve has malfunctioned. The vehicle has 54000 miles on it and the repair costs $8500. The part is only $300 but the transmission must be removed to repair the vehicle. The safety of people is not compromised by the part. The malfunction has been confirmed by the dealer.
2020 Mercedes-Benz G-Class · Engine · filed with NHTSA Jan 11, 2026 · ODI 11710210
Lock Differential error message. Mercedes Benz attempted to fix twice but it’s still reporting the error
2019 Mercedes-Benz G-Class · Electrical System · filed with NHTSA Jan 17, 2022 · ODI 11447771
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 group22 other manufacturer communications filed against the Mercedes-Benz G-Class 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 |
|---|---|---|---|
| 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… |
| 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… |
| NCU - 2026050002 | Service campaign | May 15, 2026 | Mercedes-Benz AG (“MBAG”), the manufacturer of Mercedes-Benz vehicles, has determined that on certain Model Year (“MY”) 2026 G-Class… |
| 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… |
| EW - Vacuum Pump M157 | Warranty extension | Mar 14, 2026 | In our continuing efforts to ensure the proper performance of Mercedes-Benz products and to enhance the satisfaction of our customers, Merce… |
| NCU - 2024100016 | Service campaign | Feb 28, 2026 | Mercedes-Benz AG (“MBAG”), the manufacturer of Mercedes-Benz, has determined that on certain MY 2019-2021 G-Class, S-Class and GT… |
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 NCU - 2023070021 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 NCU - 2023070021 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 NCU - 2023070021 cover?
The manufacturer filed it against 2 model years: 2020 Mercedes-Benz G-Class, 2019 Mercedes-Benz G-Class. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.