jessicawagner8
Mercedes B Klasse auxiliary battery issue
Summary of the thread
The 2011 Mercedes B Klasse was experiencing issues with the auxiliary battery, leading to error messages on the speedometer and sluggish engine starts. Diagnostic tools revealed battery-related error codes, suggesting the auxiliary battery wasn't charging properly. The problem was identified as a common battery failure, and the recommended solution was to replace the auxiliary battery. After replacement, the error messages disappeared, and the car's performance improved.
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4 comment(s)
jessicawagner8 (community.author)
Thanks for the quick reply! I don't have a multimeter, but I could probably borrow one. Where exactly do I test the voltage on the auxiliary battery? Is it the same as testing the main car battery, or are there any special considerations? I'm a bit of a novice when it comes to car electronics.
heinzwolf1
While you can test it yourself, given the electrical malfunctions you're describing, and your lack of experience, it's probably best to take it to a workshop. They can properly diagnose the charging system and confirm if it's just battery replacement or something more involved.
jessicawagner8 (community.author)
You were spot on! Took it to a trusted mechanic, and they confirmed the auxiliary battery was toast. Battery replacement and labor came out to 290€. Ouch, but at least the error messages are gone, and the car starts like a champ again. Thanks for the advice!
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MERCEDES
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BKLASSE
heinzwolf1
Sounds like classic battery failure symptoms. The auxiliary power system is crucial for many car electronics. Have you checked the battery voltage? A simple multimeter test can give you an initial idea of its condition.