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June 12, 2026 Service bulletin

Complaint The remaining time shown on the instrument cluster in the workshop menu (days to next due...

Mercedes-Benz technical service bulletin LI00.20-P-078424 for 2022-2026 Mercedes-Benz C300, 2024-2026 Mercedes-Benz E350 and 2023-2026 Mercedes-Benz GLC 300 and others.

Bulletin number
LI00.20-P-078424
Component
Electrical system
Summary
Complaint The remaining time shown on the instrument cluster in the workshop menu (days to next due service) is implausible (>365 days) for the following conditions: • for the date of the vehicle handover • or the last conducted and confirmed Service A/B Cause Case 1: Observe the following on vehicles with a disconnected on-board electrical system battery (12V/48V): • The period in which the on-board electrical system battery is disconnected cannot be counted by the maintenance computer. • As soon as the on-board electrical system battery is connected again, the maintenance computer automatically starts counting without making a correction to the remaining time (days until the next service). Case 2: If a disconnected on-board electrical system battery (12V/48V) can be ruled out as the cause, it is possible that: The daily turnover counter inside the electronic ignition lock (EIS) has experienced memory loss. This anomaly was detected in the EIS software from modification year 2022 onward. To do this, please check the plausibility of the daily turnover counter as follows: If "TUSZ Assyst Plus" < the actual days since "Handover Date/DAY/Month/Year," then proceed to remedy for case 2. Information: A variation of 2-3 days is still considered plausible. If "TUSZ Assyst Plus" is plausible, or if a remaining time of 365 days is permanently displayed, check whether the vehicle has been handed over. These types of cases have different causes. (The respective values are included in the maintenance data in the control unit log of the instrument cluster). Remedy For case 1: When the on-board electrical system battery is disconnected, this period must always be taken into account for these vehicles, and the following condition must be met for a correct calculation to be made: • (A): The number of days from the "date of vehicle handover or last service A/B" to the "date on which the vehicle arrived at the workshop." • (B): Remaining time (days until the next service, as shown in the instrument cluster). • (C): Days on which the on-board electrical system battery was disconnected. The formula requires the following condition to be complied with. 365 - (A) [days] = (B) - (C) [days] For case 2: If the on-board electrical system battery (12 V/48 V) was not disconnected and the remaining time shown in the customer or workshop menu on the instrument cluster (days until the next service) is implausible in terms of the date of the vehicle handover or the last performed and confirmed service A/B, or the condition in the formula was not met, the service can still be performed and confirmed. For vehicles arriving more than 90 days after the service due date, the DSB service history can only be corrected by re-entering "Vehicle regularly serviced." A software fix for the EIS (electronic ignition lock) is currently in planning. The objective is to have a remedy available for 2026. Until the remedy is available, it is advisable to inform the customer that the next service is due again after 365 days at the latest.

Owners of these vehicles have filed 193 complaints in the electrical category.

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