2020 Mercedes-Benz
GLC 300Problems & recalls

Complaint During part of the steering movement, it feels heavier or more difficult to steer in the same spot every time. OR Rattling, humming, dry sliding/gravel noise from the electric steering system when steering (see attachment). Complaint does not impact the ability to safely steer or control the vehicle. Cause Ball screw drive (KGT) of electric steering damaged by: 1. External force due to: ‑ Hitting the curb/posts with the front wheels. ‑ Driving over obstacles (e.g. pothole/ threshold/ speed bump/ gully) at an inappropriate speed. 2. Corrosion/ water ingress through a damaged boot (see attachment). ‑ Cracks (1) ‑ High pressure cleaner (2) ‑ Animal bite (3) See various examples listed in the attachments for examples of outside influence. Remedy Remove boot clamps closest to steering gear housing on both left and right (as seen in "Steering Rack Boot Clamp Location"). Pull back boot and inspect for rust, broken end stops, water, or any other anomalies. Replace electric steering. Note: Steering gears replaced due to outside influence or damage must not be claimed under warranty!

Components: STEERING. Confirm detailed applicability in the original document.

Complaint Tailgate opens unintentionally. Cause Accidental or unnoticed activation of the button to open the tailgate on the vehicle key. EXAMPLE: when stored in trouser pocket, handbag etc. Remedy As of the 6th generation, the vehicle key can be recoded so that the tailgate no longer opens as a result of a long press on the button, but by double‑clicking on the button instead. This reduces the likelihood of the button being activated accidentally or unintentionally. The recoding can be carried out as follows: 1. Add SA Code O19 into VeDoc (O for Oscar, not "zero") • an XSS ticket may be necessary to add the SA code 2. Perform SCN coding of EIS N73 control unit 3. Deactivate the vehicle key (a successful deactivation is indicated by the LED lighting up 2x briefly and then 1x for a long period). 4. Place the vehicle key in the storage compartment on the key symbol and turn on the ignition. IMPORTANT: all other vehicle keys must be outside the recognition range of the vehicle when doing this! Perform steps 3 and 4 successively for all vehicle keys. Notes: 6th, 7th and 8th generation keys can be deactivated as follows: Up to modification year 22/1 by double clicking the "Lock button" As of modification year 22/1, by press and holding the “Lock button", then double‑click the “Unlock button" at the same time. On model series 167, the storage compartment with the key symbol is located in the armrest. The SCN coding from the EZS is only transferred correctly to the vehicle key under the following conditions: Only one vehicle key is located in the vehicle, this key has been deactivated and it is positioned on the marking in the storage compartment for the data transfer. The costs for this adaptation are to be borne by the customer. For the newer BR 174, 178, 244, 248, 520, and 540, a software update must be initiated, as there is no way to perform SCN coding.

Components: ELECTRICAL SYSTEM · STRUCTURE:BODY. Confirm detailed applicability in the original document.

Dear Mercedes-Benz Owner: In our continuing efforts to ensure the proper performance of Mercedes-Benz products and to enhance the satisfaction of our customers, Mercedes-Benz USA is extending the warranty coverage for the Diagnostic Module for Tank Leakage Detection ("DMTL") on your vehicle from the original New Vehicle Limited Warranty of 4 years / 50,000 miles to 15 years/150,000 miles (whichever occurs first). This applies to the vehicle regardless of ownership. Why the Warranty extension? On certain Model Year 2018 - 2024 A / C / CLA / CLS / E / G / GLA / GLB / GLC / GLE / GLS / GT / S / SL Mercedes-Benz vehicles, under certain circumstances, the DMTL may trigger erroneous Diagnostic Trouble Code ("DTC") entries that may result in the illumination of the Check Engine Malfunction Indicator Lamp ("MIL"). Any repairs under this warranty extension must be performed by an authorized Mercedes-Benz dealership. • If your preferred authorized Mercedes-Benz dealership performs a diagnosis and confirms that your vehicle has the issue, the repair will be covered under this extended warranty and performed at no cost to you. • This extended warranty does not apply to any other components or conditions beyond the ones mentioned above, and standard warranty terms apply, including the exclusions with respect to extra expenses, as identified in the Service and Warranty Information booklet.

Components: FUEL/PROPULSION SYSTEM. Confirm detailed applicability in the original document.

Complaint 1. General Diagnostic Tips 2. One or More PARK Sensor Activations 3. Red Ring Around Vehicle 4. "Active Parking and Parking Assist Inoperative" on Instrument Cluster 5. Cameras 6. Other Park Topics. Cause Various root causes Remedy See attached diagnostic guide.

Components: ELECTRICAL SYSTEM. Confirm detailed applicability in the original document.

Complaint A popup is seen on the HU with the message "data connection temporarily not available". Potentially affected functionalities in NTG4.5, NTG5 1.Weather 2.Local Search 3.IP Radio 4.Send2Car 5.Speech Detection Service 6.Navigation 7.iHeartRadio 8.Traffic Cams Cause MB Apps is sundowned for all vehicles with NTG4.5 and NTG5 Head Unit Variant. Remedy No support available for NTG4.5 and NTG5 Head Unit Variants for MB App related topics. Note: Please do not create TIPS. Please do not replace any components. HU/Hermes SW update / SCN coding will not fix the issue.

Components: ELECTRICAL SYSTEM. Confirm detailed applicability in the original document.

Complaint Clanking noise from the area of the speakers in the doors. Cause Under analysis. Remedy To narrow down the cause, first of all remove the door trim. • If the noise continues to occur even with the door trim removed, then continue the diagnosis working towards the speaker and if necessary, create a TIPS case with an informative video as an attachment. Information: Please refer to this document in the warranty claim and, after completing diagnosis, select the damage code corresponding to the component part that caused the problem. • If the noise stops when the door trim is removed, please proceed in accordance with LI72.10-P-067691. Information: In this case, do not use a damage code for the speakers in the warranty claim!

Components: STRUCTURE:BODY. Confirm detailed applicability in the original document.

Complaint This document is intended as a pre-case diagnostic reference for transmission related concerns. It will also ensure that if a case is necessary, all supporting documentation is available. This should not be used on its own as justification for creating a TIPS case. Cause The root cause will vary depending on the complaint. The goal of this document is to provide diagnostic checks and procedures that may help resolve customer complaints without opening a TIPS case. Remedy Before opening a transmission-related TIPS case, the following steps must be performed to ensure all relevant data has been collected and possible remedies (when applicable) have been performed. Please Note: At minimum, the documents below must be collected before proceeding to ensure the data in its original state when the vehicle arrived is captured. - Initial Quick Test w/ Freeze frame data - VGS Control Unit Log - Initial EEPROM data (.txt format) - IPR Result (if applicable. See LI27.00-P-073124 - Transmission diagnosis using the Intelligent Predictive Repair (IPR) tool) - Transmission Heath Page If the vehicle has previously been repaired for the same concern, note the date, mileage, and TIPS case or RO number, along with a brief description of the prior work performed. IPR Guidance: The IPR recommended repair should be completed prior to following any steps in this LI and prior to case creation. IPR repairs do not require additional warranty approvals or a TIPS case to validate/confirm the results. To ensure efficient case handling, please avoid opening TIPS cases for this reason. For further information regarding IPR please see the following documents: LI27.00-P-073124 - Transmission diagnosis using the Intelligent Predictive Repair (IPR) tool Oil Pan Condition Evaluation: In some situations, IPR will advise checking the oil pan condition and determining a repair based on the evaluation. Example photos in Xentry can be found in two ways: • Use the blue hyperlink in the IPR result, and it will take you to the Condition check of transmission oil • Navigate to Xentry Bluebook > Help for control unit > Condition check of transmission oil If a different repair that what is recommended by IPR is performed, attaching photo documentation of the complaint vehicle oil pan and the IPR example to the claim is required. Reproducing the Concern: Proper evaluation of transmission concerns generally requires the condition to be reproducible. It is recommended to compare the vehicle to a similar model, if available, to help determine whether the shift behavior is characteristic of the drivetrain or uncharacteristic for the vehicle. If the concern cannot be duplicated: • A test drive with the customer may assist in understanding and reproducing the complaint. • The vehicle shift quality should be compared to a known-good vehicle with identical drivetrain and model year. • Check Shift Quality History (VGS Control Unit > Adaptations > Shift Quality History) Shift Quality History will show the last 5 noticeable harsh shifts and some of the parameters in which it occurred. You can use this to attempt recreation of the operating conditions and increase likelihood of reproducing the complaint. Complaint A: Shift Quality Note: Certain AMG variants may exhibit more firm and noticeable shift behavior as a normal characteristic. Refer to LI27.60‑P‑075147 for additional information. 1. Perform Valve flushing procedure 2. Perform 5 Torque Converter adaptions in a row - Allow the vehicle to warm up naturally, DO NOT power brake as it will increase the temperature in the torque converter. - After the 5th adaptation, collect a screen shot showing all 5 on one page 3. Perform a standstill adaption - collect a screen shot Recheck vehicle operation. If the concern has not improved, driving adaptations should be performed to target specific gear shifts.

Components: POWER TRAIN. Confirm detailed applicability in the original document.

Complaint Mercedes-Benz USA is currently experiencing limited availability of transmission fluid specification ATF 236.17 due to a global supply constraint. 236.17 ATF 1L and 5L (PNs: A002989060312 and A002989060313) bottles are out of stock or in limited supply at Zep. This LI has been created with the following intention: - Provide dealers with additional workshop-focused guidance regarding the current ATF 236.17 supply constraint and the planned introduction of ATF 236.18. - Supplement existing communications and address common workshop questions related to maintenance, repairs, and fluid applicability. - Provide technical clarification and practical workshop guidance during the temporary supply constraint period. Dealers should continue to reference the latest News Channel Updates (NCUs) for the most current information regarding availability, ordering processes, supply status, and other related updates. Cause Damage to the Shell production facility has resulted in 236.17 oil supply being reduced to 50% of normal output until the end of 2026. Remedy Please first check Latest NCU updates for latest detailed information. Please continue placing orders through Paragon as normal. Supply is expected to remain reduced and allocation measures are currently in place. We ask for your patience through this restricted supply period. Most orders will be filled in the order in which they were received, as supply is replenished. Those dealers with zero inventory, and pending orders, will receive priority. We expect supply to be stabilized in September 2026. Approved Fluids: Only use transmission fluid from the approved list found on the Mercedes-Benz Operating Fluids website. Non-approved fluid will result in mechanical damage to the transmission and must be avoided. https://operatingfluids.mercedes-benz.com/sheet/236.17 Approved fluids can be claimed as follows if there is no Mercedes-Benz part number: Part # ATFSUB1L - TRANSMISSION FLUID 1 LITER ATFSUB5L - TRANSMISSION FLUID 5 LITER Dealerships with Zero Inventory AND Grounded Vehicles: If a vehicle is currently grounded for repair at your dealer due to no 236.17 inventory, we may be able to expedite your order. Please open a StarSupport ticket including the following information: (Parts Related Inquiry>National Accounts>Zep) • LI document number • Short explanation of repair needed for grounded vehicle • Current days down of RO Maintenance and Service Interval Guidance Published maintenance intervals remain unchanged. Vehicles should continue to be maintained in accordance with the applicable maintenance schedule. This LI does not revise or extend any published maintenance interval requirements. If all required parts and materials are not available prior to scheduling or beginning a transmission service, dealers should consider postponing routine preventative transmission maintenance until the necessary parts become available. For vehicles that have not yet reached the applicable maintenance interval and do not exhibit transmission-related concerns, there is no need to recommend preventative transmission services prior to the scheduled maintenance interval. When evaluating whether routine transmission maintenance can be deferred until parts become available, dealers should consider: • Overall vehicle condition • Vehicle usage and operating conditions • Presence of transmission-related symptoms or customer complaints • Customer expectations and vehicle operating requirements • Availability of required parts and materials Introduction of New Fluid Specification 236.18 Mercedes-Benz is currently preparing the introduction of ATF 236.18 as an additional approved transmission fluid solution for applicable NAG3 transmissions. At the time of publication of this LI, ATF 236.18 is not yet available for dealer ordering or workshop use in the U.S. market. See attachment for further details.

Components: POWER TRAIN · UNKNOWN OR OTHER. Confirm detailed applicability in the original document.

This NCU replaces the prior NCU issued on May 15, 2025, and contains additional MY 2023 and MY 2024 vehicles which are highlighted below. In our continuing efforts to ensure the proper performance of Mercedes-Benz products and to enhance the satisfaction of our customers, Mercedes-Benz USA, LLC (“MBUSA”) is extending the warranty coverage on the Diagnostic Module for Tank Leakage detection (DMTL) in certain Model Year (“MY”) vehicles listed below from the original New Vehicle Limited Warranty of 4 years/50,000 miles to 10 years/120,000 miles (vehicles certified as LEV II) and 15 years/150,000 miles (vehicles certified as LEV III), whichever occurs first, for the following condition: •Under certain circumstances, the DMTL may trigger erroneous Diagnostic Trouble Code (DTC) entries that may result in the illumination of the Check Engine Malfunction Indicator Lamp (‘MIL’).

Components: FUEL/PROPULSION SYSTEM. Confirm detailed applicability in the original document.

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 (205, 463, 253, 190 & 222 platforms) vehicles, the engine control unit software does not correspond to current production specifications. It is therefore possible that on-board diagnostics and/or exhaust gas emissions requirements may not be fulfilled.

Components: ENGINE. Confirm detailed applicability in the original document.

Single throttle lift-off clunking noise from the side shaft when moving off (audible at the outboard end). The noise is heard once in each instance when changing direction of travel. Note: Sound file in attachment Cause If the complaint is eliminated by experimentally loosening the outboard collar nut (by 1 turn), the problem is due to cracking of the microweld between the wheel bearing inner race and the joint housing of the side shaft. Note: The collar nut must always be replaced after being loosened. See also LI33.20-P-078406 Remedy Coat contact surface of side shaft with wheel bearing with Molykote paint. To do this, proceed as follows: 1. Remove side shafts 2. Clean contact surface A (see image file in attachment "Outer joint housing before") before coating with Molykote, using "spirit" (free of dust and grease) 3. Coat contact surface A (see image file in attachment "Outer joint housing after") with Molykote and leave to dry for "one hour" in removed condition 4. Reinstall side shafts Note: Before using the antifriction coating (Molykote), stir it or shake it thoroughly for (at least 1 minute).

Components: POWER TRAIN. Confirm detailed applicability in the original document.

Complaint Creaking noise, in irregular sequence when driving slowly in combination with slight steering movements and/or Creaking/crackling noises from the area of the wheel bearing on the front axle when cornering/ maneuvering. Sound file attached for comparison. MUST match noise for proper diagnosis. NOTE: Steering functionality is not affected. Cause Contact area between wheel bearing and steering knuckle. See also: LI35.30-P-058566 (Throttle Lift-Off Noise - Rear) LI33.30-P-056665 (Throttle Lift-Off Noise - Front) LI40.10-P-059248 (Wheel cracking noise when cornering) Remedy 1. Perform Operation A and evaluate by testing vehicle. 2. If noise is still present after re-testing: • If 192/232 chassis, verify FIN is in the listed range below in "Operation B" and perform. • If not 192/232 chassis or vehicle is a 192/232 not in the listed FIN range, additional verifications of where the noise is coming from are needed. Use multiple channel NVH method to narrow down location. Verify the LI's listed above were completed or if there are other similar noises associated with the chassis (Example: 192/232 also has under panel noises and an associated LI). Operation A: 1. Clean contact surfaces of wheel bearing and steering knuckle with brake cleaner as seen in the attached pictures. NOTE: The front area of the wheel bearing and the seals must not come into contact with the cleaner, otherwise, the sealing rings will be damaged. 2. Clean threads of wheel bearing mounting. 3. Thinly coat contact surfaces of wheel bearing, steering knuckle, and axle mating face with Molykote (annular joint grease). See the attached steering knuckle and wheel hub pictures for reference. NOTE: Axle mating face greasing is also covered in LI35.30-P-058566 and LI33.30-P-056665. Operation B (Only applies to 192 and 232 in listed FIN range): Only affects vehicles up to FIN end number: • Model series 192: xxx xxx xx 002 876 • Model series 232: xxx xxx xx 022 312 1. Replace steering knuckle. 2. Wheel bearings do not need to be replaced.

Components: SUSPENSION. Confirm detailed applicability in the original document.