The automatic start-stop function of the Mercedes B200CDI is malfunctioning, and the instrument cluster is experiencing blackout during engine cranking.

[rab60bit88]

Approximately one and a half years have elapsed since I substituted my original Mercedes battery with a Varta cell of identical specifications.

For the past six months, the auto start-stop feature has been inoperative, which I have perceived as a hidden advantage. Recently, the cluster has blackouts on cold starts. I have communicated with the battery vendor and provided my voltage readings obtained via OBD2, which have also been verified with a voltmeter.

[rab60bit88]

[rab60bit88]

I brought the car to Mercedes today, where they examined the battery and said that it needed replacement. Xentry disclosed no errors. The auxiliary battery was likewise in good condition.

[rab60bit88]

[rab60bit88]

I brought the vehicle to the battery shop since it remained under warranty. The battery was inspected and deemed to be in good condition. They transported it to a local Exide testing centre and informed me that it was functioning properly.

The warranty replacement applies solely if the battery is entirely nonfunctional and does not revive after bench charging.


ChatGPT identified it as a weak ground strap issue. However, the Mercedes-Benz dealer asserts that such a part does not exist.

The alternatives available to me are: 1. Disregard the problem until a more significant issue arises.
Proceed to the dealership and purchase their battery (Varta, rebranded for Mercedes) for around 50,000.
Purchase an additional Varta battery for 27,000.

What actions should I undertake?

[Black_raven]

The year of your B Class is uncertain, but assuming the parts diagrams are accurate, the B200 CDI indeed possesses an engine-to-body grounding strap (W246 version): Component number 250 is located here:

[Black_raven]

https://nemigaparts.com/cat_spares/epc/mercedes/1/fg/246203/p01/54/030/

[rab60bit88]

I appreciate this. I have been searching for this part number.

[stevenkeyte]

It is likely that a new component is unnecessary; ensure that the connections are clean and provide effective metal-to-metal contact.

[QuirkyPixel]

....but, it is possible that you may. I was experiencing starting and EML troubles with one of my vehicles.The leads were satisfactory; but, upon closer examination, there was some green discolouration at the ends. When I removed the insulation from the ground lead, it revealed a deteriorated, green and black substance that disintegrated in my hands. It is remarkable that it functioned at all. New leads resolved all my concerns. Merely a small amount for general eBay items. Examine the junction where the ground attaches to the body, ensuring both surfaces are polished to a gleaming metal finish before reattaching. Additionally, inspect the periphery of its insulation. Certain vehicles, particularly some ALFAs, benefit from an additional engine-to-body ground wire. Additionally, cleanse the battery terminals and clamps, particularly if they exhibit a dark or black hue.

[rab60bit88]

I will request my dealer to verify. I assume it cannot be delivered to home? Requires placement on a lift?