Technical Service Bulletin LI20.30-P-078333 — 2023 MERCEDES-BENZ EQB 350 4MATIC

Complaint "Coolant level too low" warning message is shown in the instrument cluster. Fault code P25567B (The 'Coolant level' sensor has a malfunction. The fluid level is too low) is stored in the signal acquisition and actuation module (SAM) control unit N10. Cause The electric drive motor of the vehicle conveys air into the cooling system. The air conveyed into the cooling system leads to an air cushion forming in the expansion reservoir, which in turn causes the coolant level to fall below the warning threshold of the coolant level sensor during travel. After the cap is opened, the coolant level is once again OK. Remedy Replace the black cap A210 501 06 15 of the large working chamber of the expansion reservoir with a red cap A297 500 51 00 and increase the coolant level by 20 mm over the max. marking. On vehicles where this process does not remedy the issue, the expansion reservoir A 243 500 41 00 is replaced by the modified container A243 500 41 00 28. If the problem is still present, please create a TIPS case.