Mercedes CLK Diesel Additional Battery System Defective

I own a CLK as well, and I recall encountering a similar issue related to the car alarm and battery problem The auxiliary battery, responsible for powering systems like the alarm, can indeed degrade over time, especially with higher mileage Did the system diagnosis indicate anything specific about the battery's voltage or internal resistance This information could further validate your suspicion

Thanks for the quick reply The system diagnosis just flagged it as 'defective' without any specific voltage readings that I could see Is the auxiliary battery easy enough to access and test myself, or am I better off just replacing it outright

I understand While you could attempt to access and test the battery yourself, given the stored error and lack of specific voltage data, I would cautiously suggest consulting a trusted workshop for a comprehensive evaluation It's possible the battery is indeed the primary issue, but a professional diagnosis can rule out any underlying electrical issue or parasitic drain that might be accelerating the battery's discharge Remember, the car alarm system is connected to other systems

Thanks Appreciate the advice I'll take it to a workshop Turns out you were spot on, the auxiliary battery was indeed the culprit Cost me around 330€ to get it sorted The 'ageing battery' diagnosis was correct Cheers