Technical service bulletins are instructions a manufacturer sent its dealers about a known fault. They are not recalls and the work is usually not free, but they are the clearest signal of a problem the manufacturer already knows about.
LI28_00-N-079097_1_en
Service Bulletin/Repair Instructions
Complaint While driving through muddy / sandy/ off road terrain "4Matic Currently Unavailable" message on the dash Cause This vehicle is not equipped with a fixed force distribution AWD, rather force is only applied to the front axle according to ESP calculations. As per GF28.00‑D‑ 9900A: "vehicles with 4MATIC all‑wheel system and variable force distribution, an electronically regulated multiplate clutch integrated into the transfer case provides for the torque distribution. If the multiplate clutch is open during normal driving operation, only the rear axle drives the vehicle. If the clutch is closed, the front axle comes into play." The message "All‑wheel drive temporarily unavailable" is not indicative of a malfunction but rather informs the driver that all‑wheel drive is currently not available due to the transfer case clutch overheating. This occurs when the vehicle is driven in such a way that maximum front axle torque is needed for an extended period, causing the clutch to get excessively hot. If the vehicle is being driven under heavy load conditions, like in deep sand or snow, the rear axle may slip while the front axle does not deliver power. The transfer case then attempts to distribute torque to correct the slip, but it is limited to a maximum of 1150 Nm to protect the front axle transmission. In extended heavy‑load scenarios, the multidisk clutch in the transfer case slips, increasing the temperature. If the temperature model detects a critical temperature of 240°C, the system protects itself by disconnecting until it cools down to around 160°C, after which the all‑wheel drive becomes available again and the warning message disappears.Vehicles can handle flat terrain easily, but steep slopes or situations where wheels slip might cause additional resistance, leading to the described protection events and message in the dash. Remedy Recommendation is to release the vehicle back to the client with an explanation that the vehicle is operating as designed. Please advise the client to limit vehicle acceleration in limited traction situations to avoid disabling of the 4Matic system ‑ please see "Notes on all‑wheel drive" provided in the operators manual.
LI54_30-N-080701
Service Bulletin/Repair Instructions
ASSYST PLUS service reminder appears earlier than expected due to vehicle operating conditions Complaint The ASSYST PLUS service reminder appears earlier than expected. The customer or dealer may report that the vehicle did not reach the starting maintenance interval shown in vehicle documentation, option coding, sales literature, or the Owner's Manual. The service reminder may appear significantly earlier than anticipated even though no faults are stored and no malfunction is present in the vehicle. The remaining distance and remaining time continue to decrease normally until the service reminder is displayed. Cause This condition is not caused by a malfunction of ASSYST PLUS. ASSYST PLUS is a dynamic maintenance management system that continuously evaluates vehicle usage and opera-ting conditions to determine maintenance requirements. The starting maintenance interval specified by variant coding represents a maximum interval that may only be achieved under favorable operating conditions. Actual maintenance intervals may be significantly shorter depending on vehicle use. Vehicle operating conditions such as driving conditions, engine load, engine operating conditions, idling, short-trip operation, environmental influences, oil aging, and Diesel Particulate Filter (DPF) regeneration activity may reduce the maintenance interval from its starting value. These conditions may accelerate engine oil aging through increased soot loading, fuel dilution, moisture accumulation, and additional engine operating stress. As a result, the remaining distance and remaining time until the next service may be reduced from the starting maintenance interval. Remedy Do not replace any parts. A due service must be assumed if the maintenance data calculated by ASSYST PLUS indicates that service is required.
LI14.20-N-073867
Service Bulletin/Repair Instructions
Complaint Complaint A: The engine is jolting/bucking between 1700 and 1900 rpm. Complaint B: One or more mechanical related fault codes for EGR Valve stored in CDI control unit, with possible Check Engine Light. Review list of mechanical fault codes in table below. NOTE: If one or more electrical related fault codes for EGR Valve are also present in CDI, utilize Complaint C. Review list of electrical fault codes PDF document in attachments. Complaint C: One or more electrical related fault codes for EGR Valve stored in CDI control unit, with possible Check Engine Light. Review list of electrical fault codes PDF document attached. NOTE: This LI supersedes LI14.20-N-073813, which is no longer valid. Cause Cause of Complaint A: Increased friction between the EGR Valve blade and seat due to soot deposits causing a delay of the EGR Valve being able to reach the target value of the EGR Valve position controller. NOTE: This causes the EGR Valve blade and potentially the boost pressure controller to oscillate. Cause of Complaint B: Soot deposits between the EGR Valve blade and seat leading to the EGR Valve no longer being able to meet the de-sired target of the EGR Valve position controller. Cause of Complaint C: Internal EGR Valve or other electrical faults related to the EGR Valve function. Remedy Remedy for Complaint A: Perform the following steps: 1. Disable the EGR Valve (Y27/17) by disconnecting the electrical connector. 2. Perform a test drive to check if the jolting/bucking issue resolves. 3. If the jolting/bucking is resolved, proceed to Remedy for Complaint B. 4. If jolting/bucking is still present, proceed with diagnosis to determine the root cause. Consider checking the follo-wing, but not limited to: •EGR system including the EGR Cooler, EGR Bypass Flap, EGR Temperature Sensor, and pipes for proper operati-on, excessive sooting and/or clogging, as well as EGR Bypass Flap vacuum element, switchover valve, and vacuum system. •Visually check the leak oil line or T-piece; reference LI07.00-N-059118.
LI49.10-N-080528
Service Bulletin/Repair Instructions
OM642 DPF Filter Cracked or Broken Complaint Vehicle will not start or exhibits noisy exhaust. Check Engine Lamp (CEL) is on. Multiple control unit communication and system faults may be present, including but not limited to: 134800, 134900, 11B300, 11EC00, 15E100, 155700, 162500. Additional events codes may include: 134300, 102200, 163400, 16CE00. In many cases, multiple unrelated faults are stored due to electrical disruption from wiring damage rather than indivi-dual component failure. Cause The DPF filter is cracked, broken, or leaking, allowing hot exhaust gas to escape from the exhaust system. Depending on the location of the break or leak, hot exhaust gas may be directed toward the main wiring harness and/ or the SCR (Selective Catalytic Reduction) dosing valve assembly. This heat exposure can result in: • Internal melting of wiring insulation within the harness • Short to ground conditions and loss of communication between control units • Damage to the dosing valve and/or heated AdBlue line Damage to the wiring harness may not be visible externally, as the outer tape can remain intact while the internal wires are melted and fused together. Remedy Inspect the DPF assembly for cracks, separation, or leakage. Do not proceed with further diagnosis or component replacement until the exhaust leak source has been identified and confirmed. If any damage is found, replace the DPF filter assembly. Based on the location of the failure, inspect all components in the path of the exhaust leak, including the dosing valve assembly and main wiring harness. The wiring harness must be opened in any area exposed to the exhaust leak to visually inspect the individual wires. External inspection alone is not sufficient to determine harness condition. Repair or replace any damaged wiring in accordance with approved repair procedures. Replace any dosing system components that show signs of heat damage. Failure to identify and repair all heat-affected components will result in repeat faults or no-start conditions.
LI49-20-N-080376
Service Bulletin/Repair Instructions
The check engine light is illuminated, or the AdBlue warning is active, with recorded faults related to AdBlue quality or concentration. Complaint Customer reports an illuminated check engine light and or an AdBlue system warning indicating AdBlue quality out of specification. The vehicle may enter reduced performance mode. One or more of the following fault codes related to the AdBlue tank may be stored: P206B31: Malfunction of the concentration sensor for AdBlue; the signal is absent. P203B31: Malfunction of the AdBlue fill level sensor; the signal is absent. P300494: The quality of the AdBlue is insufficient. Background AdBlue must meet ISO 22241 quality requirements. ISO 22241 urea content limits for AdBlue are 31.8 percent to 33.2 percent by mass. AdBlue begins to crystallize and freeze at approximately 12 degrees F. Freeze-thaw does not degrade the product when uncontaminated, and the bulk concentration returns to normal after complete thaw and mixing. Cause In cold soak conditions and during freeze thaw exposure, the tank contents may not be uniform at the time of sampling or system checks. During freezing and partial thaw, ice formation can temporarily create concentration gradients in the tank. As a result, urea percent readings can vary based on sample location and the state of thaw and mixing, which can produce apparent out of range readings even though the bulk fluid returns to normal after mixing. Remedy Testing Do not use a single urea percent reading taken from frozen, partially frozen, or not fully mixed AdBlue to make a repair or responsibility decision. Confirm full thaw and ensure tank contents are mixed before sampling. 1. Confirm full thaw - Confirm the AdBlue tank and associated components are fully thawed before sampling. - Do not sample slushy or partially frozen fluid. 2. Mix tank contents - Perform a road drive intended to mix the tank contents before sampling. - Idle time alone is not a reliable substitute for mixing. 3. Sample and measure - Take the sample and measure with the MB refractometer per the MB tool instructions. - Record the urea percent value. 4. Interpret the result against ISO 22241 limits - Within specification is 31.8 percent to 33.2 percent urea by mass. 5. Repeat if out of specification - If out of specification, repeat after an additional mixing drive to reduce sampling variation. - If still out of specification after full thaw, mixing, and repeat measurement, treat as a true out of specification result and proceed with further diagnosis per applicable MB guidance. Acceptance criteria AdBlue is within the ISO 22241 specification when the urea percent is between 31.8 percent and 33.2 percent by mass. Values outside this range are out of specification and require further diagnosis after completing the full thaw and mi-xing procedure above. Cross reference For vehicles with fault codes P206B31, P203B31, or P300494, refer to LI49.20-N-078838 for the detailed diagnostic and repair procedure. If a SCR or AdBlue warning reset is required after correction, refer to LI49.20-N-075995. Complete the diagnostic and corrective steps first. Perform the warning reset only after the underlying fault condition has been corrected. Warranty information and claim handling
LI28.00-N-063339
Service Bulletin/Repair Instructions
Clunking noise on load change or gear engagement Complaint Clunking noise can be heard on some load changes or when changing from N->R or N->D Cause Movement of transfer case splines Remedy Apply bearing retainer (green) Loctite to both output shaft splines of the transfer case. Loctite 648, 609 and 603 are acceptable for this repair. Note: Do not apply Loctite to input shaft (connection with transmission) splines of the transfer case else possible damage could occur.
LI54.30-N-079757
Service Bulletin/Repair Instructions
Engine Oil Level Cannot Be Checked via Instrument Cluster Service Menu Complaint Sometimes the engine oil level cannot be determined using the instrument cluster's service menu. The following mes- sages may be displayed: •Engine oil level currently inoperative. See Attachment: Message "Engine oil level currently inoperative" (shown in German on model 907 with code C6L (Multifunction steering wheel)). •Engine oil level measurement is running. Repeat the query after a maximum of 30 minutes of driving time. Information: It is still possible to determine the engine oil level via the workshop menu or XENTRY Diagnostics. Cause No current value for the saved oil volume has been stored in the drivetrain control unit (CPC, N127). Remedy 1. Connect diagnostic device (see AD00.00-D-2000-06TS for model 907). •Always use the latest XENTRY Diagnostics software release with all available add-ons. •Follow all operation steps in XENTRY Diagnosis precisely. 2. Perform initial quick test (see AD00.00-D-2000-06TS for model 907). •Print out the initial quick test as a PDF file and attach it to the order in a tamperproof manner. 3. Create and save the control unit log for drivetrain control unit (CPC, N127). •Print out the control unit log as a PDF file and attach it to the order in a tamperproof manner. •Check the saved oil volume in the "Maintenance data" tab of the control unit log. See Attachment: Saved oil volume in "Maintenance data" tab of the control unit log (shown in German). •If the saved oil volume in the "Maintenance data" tab is more than 0.0 liters and it is not possible to determine the en- gine oil level via the service menu, conduct further research on the exact reason for the customer complaint and initia- te corresponding repair measures. •If the saved oil volume is 0.0 liters, proceed with operation step 4. 4. Check actual values for engine oil level in the engine control unit and observe any relevant information and descrip- tions in XENTRY Diagnosis. •Quick test view → Engine control unit → Actual values → Oil circuit → Oil level gauge 5. Clear fault memory (see AD00.00-D-2000-06TS for model 907). 6. Disconnect diagnostic device (see AD00.00-D-2000-06TS for model 907). 7. Carry out a test drive of more than 30 minutes, run the vehicle in idle for approximately 3 minutes on a level sur- face, switch the ignition off and on again, and then record the engine oil level again using the instrument cluster's ser- vice menu. •Only carry this out if the saved oil volume in the "Maintenance data" tab is 0.0 liters. •When checking the engine oil level via the service menu, refer to the operator's manual. Inform the customer accor- dingly about these circumstances. See Attachment: Message "Engine oil level OK" (shown in German on model 907 with code C6L (Multifunction steering wheel)). 8. If the customer complaint occurs again, create a TIPS case directed to the Powertrain inbox, including all required information from this LI.
LI27.19-N-079793
Service Bulletin/Repair Instructions
Complaint Transmission control unit Y3/8n4 (fully integrated transmission control unit (VGS)) not listed in quick test and/or no communication possible with VGS. Cause Transmission control unit Y3/8n4 Remedy For vehicles with 722.9 transmission: Ensure LI54.15-P-057373 is performed before replacing any component parts. After processing and complying with the above document(s): 1. Perform an ignition reset on Y3/8n4 (VGS) 2. Inspect transmission connector for loose connections, damaged wiring or pins and any other concerns. If communication with the VGS cannot be established, the complete valve body ('electrohydraulic controller unit (EHS)') must be replaced. Installation of a VGS repair kit is not permitted in this case as it is not possible to transfer the necessary valve characteristics without communication with the original control unit.
LI47.10-N-079010
Service Bulletin/Repair Instructions
Procedure for When Diesel Fuel Tank is Filled with Incorrect Fuel Type Complaint: Procedure for When Diesel Fuel Tank is Filled with Incorrect Fuel Type (e.g., gasoline, water, biodiesel, AdBlue/DEF) Cause: The incorrect fuel type, such as gasoline, water, biodiesel, or AdBlue/DEF has been added to the fuel system.
LI82.35-N-078930
Service Bulletin/Repair Instructions
Warning Lamp "Washer Fluid Empty" Yet Reservoir Is Not Empty Complaint: Warning lamp "washer fluid empty", even thought the washer fluid reservoir is full Cause: Insufficient electrical conductivity of the washer fluid, as the washer fluid was mixed with distilled water. Tip: The washer fluid sensor detects the electrical conductivity. If air is present without electrical conductivity between the measuring points, as is the case with an empty tank, an empty tank is detected by the sensor. Distilled water also does not have electrical conductivity, meaning that the sensor detects an empty tank, even if this is not the case. Remedy: Fill reservoir with standard washer fluid and water (no distilled water) in an adequate ratio in order to ensure electrical conductivity. Exchange of the reservoir with a welded-in sensor is only required if filling with conductive washer fluid has not provi- ded a remedy. This can be made certain by utilizing water with a light amount of salt dissolved in to it for stronger con- ductivity.
LI07.70-N-078824
Service Bulletin/Repair Instructions
Complaint Fault code P06DA00 is found current or stored in engine control unit. Check engine light may be activated. Cause Various causes Remedy Up to Model year 2018: Fault code P06DA00 can be disregarded if not activating the check engine light, unless otherwise specified in the gui- ded test. The vehicle continues to operate as designed. Further causes should be investigated if complaint of check engine light is received. Model year 2019 and later: Fault code P06DA00 will activate check engine light as of model year 2019. No driveability concerns will be observed, only illumination of the CEL. This fault code indicates high resistance or open in the circuit to Y130 oil pump control valve. Perform guided test for component Y130 under list of tests in ME. Diagnose location of high resistance or open in Y130 circuit and repair as necessary. Warranty claims submitted without supporting guided test results may be subject to debit.
LI49.20-N-078838
Service Bulletin/Repair Instructions
Complaint The check engine light or AdBlue warning is activated, accompanied by one or more of the following fault codes rela- ted to the AdBlue tank: P206B31: Malfunction of the concentration sensor for AdBlue; the signal is absent. P203B31: Malfunction of the AdBlue fill level sensor; the signal is absent. P300494: The quality of the AdBlue is insufficient. Cause A. The software for the AdBlue (SCR) control unit (N118/5) is outdated. B. The concentration of AdBlue is either above or below the Mercedes-Benz specifications, which can lead to prema- ture freezing. C. Frozen or partially frozen AdBlue can cause the AdBlue level sensor to misread levels. D. The AdBlue level sensor is damaged. Remedy A. Software 1. Verify no newer software in AdBlue® SCR control unit (N118/5). 2. Complete LI49.20-N-075995 for Adblue warning reset. --NOTE-- If there is no updated software available, proceed to step B. B. Adblue Concentration 1. Verify the AdBlue concentration according to WIS AR49.20-D-9264TS - Check the concentration of AdBlue. --NOTE-- If the AdBlue concentration is below 31.8% or above 33.2%, it must be replaced. Please note that this will be at the customer's expense. 2. If the AdBlue concentration is within the approved specifications, please proceed to step C. C. Frozen Adblue or the SCR Actual Values state 'Frozen Adblue' 1. Check if the AdBlue is frozen. If it is, let the vehicle sit in a warm place overnight and recheck. 2. Have the vehicle running and XENTRY hooked up displaying Adblue level values 3. Drain the Adblue Tank and verify fill level reflects the change in the Adblue level 4. Fill the Adblue Tank SLOWLY and do not overfill, verify fill level reflects the change in the Adblue level --NOTE-- The Fill Level Sensor 1 functions as the "empty sensor." It accurately measures the bottom 60 mm (2.3 in- ches) of the AdBlue tank. Once the tank is filled beyond the 60 mm (2.3 inch) mark, the sensor may not read accura- tely, and you might notice the displayed value fluctuating. This behavior is normal, see attachment 'Fill Level 1'. 5. Reset the Adblue Tank fill level via XENTRY --NOTE-- If the XENTRY still shows that there is frozen Adblue or the concentration is still inaccurate after draining and filling, please refer to the attachments 'Adblue Frozen' and 'Adblue Concentration' and proceed to step C. 6. Complete LI49.20-N-075995 for Adblue warning reset. --NOTE-- If the steps above do not fix the vehicle, please proceed to step D. D. Damaged Adblue Level Sensor/Concentration Sensor 1. Replace the Adblue Tank 2. With the vehicle running and XENTRY hooked up displaying Adblue level values 3. Fill the Adblue Tank SLOWLY and do not overfill, verify fill level reflects the change in the Adblue level 3. Reset the Adblue Tank fill level via XENTRY 4. Complete LI49.20-N-075995 for Adblue warning reset. --NOTE-- During LI49.20-N-075995 for Adblue warning reset, please ensure that the outside temperature sensor is reading above 10 degrees Fahrenheit. If it is not, keep the vehicle inside the shop overnight. Complete LI49.20- N-075995 again. Additionally, please note that the vehicle may need to be driven to allow the NOx sensors and SCR system to complete their self-test. Once this is finished, the P13DF00 code should be stored and can then be cleared. --NOTE-- During cold weather, when temperatures are below 32 degrees Fahrenheit, please advise the client to keep the AdBlue tank fill level between 50% and 85%. This will allow for proper fluid expansion and help prevent damage to the level/concentration sensor.
LI49.00-N-078608
Service Bulletin/Repair Instructions
SMOG/Emissions Test fail due to one or more Readiness Monitors not set Complaint: The vehicle has failed the State Emissions Certification because one or more of the OBDII readiness monitors are not completely set. Cause: One or more of the following Readiness Monitors are not fully set within XENTRY: Misfire Monitoring - Injection System Fuel System Monitoring - Injection System, Fuel System, EGR Valve, O2 Sensor NMHC Catalyst Monitoring - NMHC/Diesel Oxidation Catalyst NOx Aftertreatment Monitoring - SCR Catalyst System Boost Pressure System Monitoring - Turbocharger, Charge Air System Exhaust Gas Sensor Monitoring - O2 Sensor, NOx Sensors Diesel Particulate Filter Monitoring - Diesel Particulate Filter System Exhaust Gas Recirculation System Monitoring - EGR Valve and system Remedy: Please complete the required driving conditions to fully set the incomplete Readiness Monitor. DO NOT: - Erase any fault codes. If fault codes are present, process these and allow the readiness drives to clear fault codes. - Flash or SCN code the CDI or SCR control units. - Perform a manual DPF regeneration, unless instructed below. - Disconnect the main battery.