Mercedes-Benz EQB 250+ X243

This is the most serious EQB issue. Mercedes-Benz has issued three recall campaigns for EQB 250+ models built between December 2021 and May 2024 with Farasis Energy battery cells. The cells can develop internal short circuits at high states of charge, potentially causing thermal runaway and fire. After two previous software-only fixes failed to fully resolve the issue (post-repair fires were reported in Europe), Mercedes committed in January 2026 to full battery pack replacement at no cost. Approximately 51,729 vehicles worldwide are affected (4,677 in Germany). Until the battery is replaced, owners are advised to limit charging to 80% and park outside. Cost to the owner is zero because Mercedes covers the replacement, but verify with the VIN that the recall has been completed or is scheduled. This is a critical check before any purchase.

A common issue across Mercedes EQ models. The 12V battery is charged via a DC-DC converter only when the car is in Ready mode or during high-voltage charging. If the car sits parked for 1-2 weeks without being driven or charged, the 12V battery can drain below the threshold needed to wake the high-voltage system. Symptoms include the car failing to unlock, dashboard warnings, or complete refusal to start. Mercedes has released software updates to improve 12V management, and later production cars (2024+) have improved DC-DC converter behaviour. Replacement of the 12V battery costs €150-350 depending on the battery type (standard vs AGM). Using a trickle charger during extended parking prevents the issue entirely.

The MBUX infotainment system can freeze, display a black screen, or reboot mid-drive. This affects navigation, climate controls, and the reversing camera. Early 2021-2022 cars are most commonly affected, and Mercedes has released multiple OTA software updates (up to MBUX 2.6.1) that significantly improve stability. A soft reset (holding the power button for 10 seconds) resolves most temporary freezes. If the head unit hardware fails, replacement costs approximately €300-400 out of warranty. Ensure the car is running the latest software version before purchase.

Cars that received the recall software update (before the full battery replacement became available) may have reduced DC charging speeds and slightly lower usable battery capacity. Some owners report maximum charging speeds dropping from 100 kW to 30-60 kW, with sessions taking significantly longer. This is a deliberate safety measure by the BMS software to protect the affected battery cells. Once the full battery pack replacement is completed under the latest recall campaign, normal charging speeds should be restored. If you are considering a car that has only received the software update (not the battery replacement), factor in the reduced charging capability.

A known issue on early production EQA and EQB models. The electric drive module can develop inadequate seals in the cooling circuit, allowing coolant to leak into the motor windings. Because the motor is a sealed unit, internal coolant contamination cannot be repaired and requires complete motor replacement. Mercedes recalled over 8,000 EQA/EQB units in China for this issue, though European-built cars appear to be less affected. The front motor replacement costs €3,000-6,000 including labour at a Mercedes dealer. Symptoms include coolant level warnings, reduced power messages, or complete loss of drive. This primarily affects early 2021-2022 production cars.

Some EQB owners report recurring coolant level warnings that are not caused by actual leaks. The coolant reservoir has multiple chambers that can become unbalanced, triggering a caution message. Mercedes released a technical bulletin addressing the coolant cap pressure release valve, and in many cases the fix is simply replacing the cap (approximately €30-50) or topping up coolant. However, any coolant warning should be investigated immediately, as it could also indicate a genuine motor seal leak. Have the dealer check for the known expansion tank imbalance issue versus an actual leak.