CNIDog

Main battery is in engine compartment on passenger side under cabin air intake. Nothing in trunk.

Where is the 2nd battery?

It's a 2012 c350 4matic 4dr sedan with sport pkg.

Funny thing, this one has only one engine air filter housing on the passenger side of the v6 engine. All the pics I've seen show two air filters on either side on top of engine. What engine option is this?

alecmascot

As you have the car in question, What engine type is it ? M???
Or post your VIN. :-))
Why do you think there should be a second battery ?

Colin G

No 2nd battery.

handyman762

2nd battery only wen car has start/stop system

CNIDog

Got it. I was reading all kinds of stuff that was confusing me. We have the Canadian edition of the C350 4matic with the M276 Blue Efficiency engine. Love it. Sport suspension pkg. Only wish they had a wagon version in the C-class.