Mercedes-Benz bulletin LI01.20-N-079115_1
What it saysCheck engine light illuminated - Fault code current P04D-B79 The crankcase ventilation system is interrupted. NHTSA’s full summary ↓
Mercedes-Benz filed this with NHTSA as a service bulletin dated Apr 3, 2025, received May 2, 2025, about the engine. It names 13 model years (2016–2023). 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.
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What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationCheck engine light illuminated - Fault code current P04D-B79 The crankcase ventilation system is interrupted. Complaint: Check engine light on. Fault code P04DB79 is current in the engine control module (N3/10). Cause: Open circuit or high resistance to crankcase vent line contact Remedy 1. Check the electrical connector for S208 vent line contact switch. Refer to attached photo of connection location. 2. Ensure the bolted connection is secure and bolt can be torqued (9Nm). 3. Check continuity from vent line connection to ME control unit. Repair wire if damage is found.
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| LI01.20-N-079115_1 | Service bulletin | Apr 3, 2025 | 11017558 | PDF, 281 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 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 13 model years this bulletin names have filed 581 complaints with NHTSA since 2015. 70 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.
on 08-03=23, I as driving MB sprinter van on highway Route 84 east toward Connecticut, when I was near Southington exit smoke was coming out of AC vent, I took exit to route 10 and stopped van right after exit on the road, and opened hood, there was active fire near lower left side engine, with help of drivers who stopped behind me, I…
2020 Mercedes-Benz Sprinter · Engine · filed with NHTSA Aug 22, 2023 · ODI 11539986
The ECM harness was wired too close to a sharp metal piece within the engine bay, the clip MBZ uses to secure it was insufficient to hold it back, the thick wiring harness got caught on the metal piece and overtime got cut deeply causing a short with thermal issues spreading to other components, the wiring harness melted together and…
2023 Mercedes-Benz Sprinter · Engine · filed with NHTSA Oct 8, 2026 · ODI 11769942
Vehicle experienced Crankcase ventilation component failure at low miles of 31,750. Code thrown is P052E resulting in needing replacement of a large assembly of emissions/oil vapor control tubing and valves costing over $1000 plus over 12 hours of labor. Well known problem on Mercedes vehicles with the M274 2.0 turbo 4cylinder engine
2017 Mercedes-Benz Metris · Engine · filed with NHTSA Apr 7, 2023 · ODI 11515978
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 group32 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 |
|---|---|---|---|
| LI20_10-N-080868_2_en | Service bulletin | Sep 2, 2026 | Coolant warning light (MIL) lights up on the display Complaint The coolant warning lamp may be displayed in the instrument cluster. The malf… |
| LI09_41-N-079165_2_en | Service bulletin | Aug 3, 2026 | Complaint Low Coolant warning with possible engine misfire caused by a leaking Charge Air Cooler (Intercooler), accompanied by one or more o… |
| LI07.16-N-080731 | Service bulletin | Jun 18, 2026 | Complaint The customer reports an exhaust odor from the engine compartment, potentially accompanied by a check engine light and/or engine mi… |
| LI14.20-N-073867 | Service bulletin | Jun 15, 2026 | Complaint Complaint A: The engine is jolting/bucking between 1700 and 1900 rpm. Complaint B: One or more mechanical related fault codes for… |
| LI09.41-N-080666 | Service bulletin | Jun 3, 2026 | Check engine light with reduced power –P300A6D due to charge air system contamination Complaint The check engine light is activated, accompa… |
| LI05.30-N-080518 | Service bulletin | Jun 3, 2026 | OM654 Extended engine crank or starting concerns and/or poor running characteristics Complaint One or more of the following may be reported:… |
| LI4910-N-060969 | Service bulletin | Apr 18, 2026 | Complaint Rattling noise from underneath the vehicle. Cause One or more of the following conditions may be present: 1. The exhaust bracket f… |
| LI49.20-N-075995 | Service bulletin | Mar 23, 2026 | Vehicles with SCR Generation 4: SCR/AdBlue® warning message cannot be reset with fault code P13DF00 or P300685 Complaint SCR or AdBlue warni… |
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 LI01.20-N-079115_1 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 LI01.20-N-079115_1 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 LI01.20-N-079115_1 cover?
The manufacturer filed it against 13 model years: 2023 Mercedes-Benz Metris, 2022 Mercedes-Benz Metris, 2021 Mercedes-Benz Metris, 2020 Mercedes-Benz Metris, 2019 Mercedes-Benz Metris, 2018 Mercedes-Benz Metris and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.