W205 / W213 Auxiliary Battery Malfunction
If this Mercedes light just popped up for you, don’t panic yet
FAULT CODES
Auxiliary Battery Malfunction
DESCRIPTION

Auxiliary battery faults on W205 and W213 models can trigger multiple electrical warnings and disable certain vehicle functions. Often mistaken for a failing main battery.

‍

COMMON SYMPTOMS & CAUSES
  • Weak or failed auxiliary battery
  • Faulty voltage limiter / converter
  • Wiring or connector issues
  • Energy management system faults

‍

DIAGNOSTIC INSIGHT

Corrosion on the auxiliary battery is a common finding on these models when left too long. Replacing early avoids further electrical faults cascading through the system.

RECOMMENDED PART
Mercedes Auxiliary Battery
Affiliate link – I may earn a commission at no extra cost to you.
View on eBay ›
IMPORTANT NOTE

Replacement or coding of auxiliary batteries and voltage limiters should be carried out by a Mercedes dealer or qualified specialist. Incorrect installation or failure to register components may lead to further electrical faults.