Mercedes CLK Battery Drain Issue

A low battery situation in a Mercedes CLK can stem from several sources. The symptoms you describe, particularly the error messages and flickering lights, do point toward an electrical system problem. Has the vehicle battery been load tested recently? A faulty battery, even if new, can exhibit similar symptoms. The battery sensor is a plausible culprit, given its role in monitoring the battery's condition and communicating with the car's computer.

Thanks for the quick response. I haven't load tested the battery, that's a good point. If the battery sensor is defective, would that definitely cause a heavy battery drain even when the car is off?

Yes, a defective battery sensor can indeed cause a significant battery drain, even with the ignition off. The sensor provides data to the vehicle's energy management system. If the sensor is providing incorrect data, the system may not properly shut down certain modules, leading to excessive current draw. Given the age of your vehicle and the symptoms, it's advisable to have a workshop confirm the diagnosis and check for any other potential issues in the electrical system that may be contributing to the battery failure.

Appreciate the confirmation, especially about the sensor causing drain while off. I took it to a workshop and they confirmed it was a defective battery sensor. Repair cost was 315€. Thanks again for your help!