Mercedes ML Electrical Issues Resolved

Overvoltage issues in modern vehicles, especially Mercedes, can stem from a failing car battery. The car electronics are sensitive to voltage fluctuations. Before complex diagnostics, confirm the battery's condition. Load test the battery to check its capacity. A weak battery can cause erratic readings. Ensure the battery terminals are clean and tight. Overvoltage can damage the car ECU, so quick action is important. Has the battery been replaced recently?

Thanks! I haven't replaced the car battery recently. It's been at least four years. Where should I connect the load tester to get a reading? Is there a specific voltage I should look for as a 'pass' or 'fail' point? I want to interpret the results correctly before worrying about a fried car ECU.

Given the age of your battery and the symptoms, a faulty battery is a suspect. Connecting the load tester directly to the battery terminals will give you the most accurate reading. A healthy 12V car battery should maintain above 9.6 volts under load. If it drops significantly below that, the battery is failing. Due to the complexity of the errors and system failures, have a workshop perform a diagnostic check to prevent further damage. Do not rely on the voltage alone, even if marginally low it could still be the issue. A professional should confirm your observation.

You were spot on. I took it to a workshop, and it was a heavily discharged and defective car battery. They replaced it, cleared the fault codes, and everything is running smoothly now. The final repair cost was 290€, which is better than a new car ECU. Thanks so much!