{"nhtsa_id":11028649,"type":"service_bulletin","type_name":"Service bulletin","date_added":"2026-02-07","date":"2026-02-07","document_id":"LI27.60-P-079083","mfr_campaign":null,"replaces":null,"component":"POWER TRAIN","mfr_system":null,"summary":"Complaint • Harsh 1-2, 2-3, and/or 3-4 shift • Jerky shifting • Jolting when accelerating from stop Cause Insufficient software application causing elevated K81/K27/B05 fill time adaptations and elevated torque adaptations for concerning shift. Remedy As of 1/28/2026 the resolution software has been released. With this software update, the transmission will adapt less often during normal driving. This will reduce the frequency of the customer experiencing the concern by ensuring the learned adaptation values stay within acceptable range for longer. Please ensure your Xentry machine is up to date with the latest Add Ons and continue with the following steps: Note: ALL steps must be performed to rectify concern 1. Perform software update for VGS control unit (A 001 902 20 34) 2. Check transmission oil level and correct, if necessary (transmission oil temperature > 60 °C) 3. Perform Xentry Valve Flushing procedure at least 3x 4. Perform a standstill adaptation, then read out new EEPROM data 5. Perform driving adaptation(s) while adhering to the below parameters for at least 20-30 miles until the shift quality improves. Note: There is no menu in Xentry for this procedure. We recommend displaying the torque in the instrument cluster. If all below parameters are met at the time the shift, a driving adaptation will automatically occur. Harsh 1-2 Perform a driving adaptation of 4-5 (adapts K81 for the 1-2 shift) Harsh 2-3 Perform a driving adaptation of 2-3 (adapts B05 directly) Harsh 3-4 Perform a driving adaptation of 3-4 (adapts K27 directly) - Level track (no incline/decline) - Slippery drive program - Display the torque in the instrument cluster: The torque must be between 100 and 250 Nm (about 184 ft lbs), preferably closer to the maximum torque - Constant engine torque - Engine speed below 2500 rpm - Do not shift via paddle If the vehicle returns and already has the updated software, please submit a TIPS case to the Powertraininbox and ensure the following is included: - Initial Quick Test w/ Freeze Frame Data - VGS Control Unit Log - Initial EEPROM (before any adaptations or Xentry procedures were performed) - Detailed vehicle history of the complaint","document":{"url":"https://static.nhtsa.gov/odi/tsbs/2026/MC-11028649-0001.pdf","alternate_url":"https://static.nhtsa.gov/odi/tsbs/2026/MC-11028649-9999.pdf","confirmed":false},"url":"https://open.wenmarpro.com/bulletins/11028649","components":[{"id":"powertrain","name":"Transmission and driveline","parent":null}],"codes":[],"topics":[],"vehicles":[{"make":"MERCEDES-BENZ","model":"AMG GLC43","year_from":2024,"year_to":2024,"match":null,"vehicle_ids":[]},{"make":"MERCEDES-BENZ","model":"AMG GLC43 4MATIC","year_from":2024,"year_to":2026,"match":null,"vehicle_ids":[]},{"make":"MERCEDES-BENZ","model":"AMG GLC43 4MATIC COUPE","year_from":2024,"year_to":2025,"match":null,"vehicle_ids":[]},{"make":"MERCEDES-BENZ","model":"GLC43 4MATIC COUPE","year_from":2026,"year_to":2026,"match":null,"vehicle_ids":[]}],"as_of":"2026-10-19","note":"A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.","attribution":[]}