“Coolant level too low” warning with a properly filled reservoir (EQA and EQB, P25567B)

Engine / equipment

Mercedes EQA and EQB electric (platform 243)

Period mentioned

2022–2025

Symptoms

While driving the coolant-level-too-low message appears and the yellow warning light comes on, with P25567B stored; when the cap is opened the level is fine again.

Possible cause described

According to Mercedes-Benz bulletin LI20.30-P-078333 (2024 and 2025), the electric motor pushes air into the cooling circuit; an air cushion forms in the expansion reservoir and, while driving, the level drops below the sensor threshold although no coolant is missing.

Check for the garage

Do not top up blindly or open the reservoir when hot. If the level is right when cold and there are no leaks, the garage swaps the black cap of the large chamber for the red one and raises the level about 20 mm above the maximum; if that is not enough, it fits the modified reservoir. If the level really drops, look for a leak.

Cost cited in the source

No verified estimate; ask the garage for a quote.A rough figure from the original database, not an up-to-date quote.

Sources from the original database