2015 C300 has slow/long/rough turn over and start + CEL
About two months ago 60k service, spark plugs, and had to replace the auxiliary battery after getting an "auxiliary battery malfunction" error in center gauge cluster screen. Made it about a month or so with no problem. Wife drives the car two miles to the train station in the mornings, two miles back. This afternoon when she got in the car to come home it gave her a rough start and popped a CEL.
"Rough start" more like it takes twice as long to crank, so like... two seconds instead of one and the car wiggles a bit. Nothing catastrophic sounding or feeling.
I'm going to try and get the codes read. I kinda suspect it was the auxiliary battery as that was done during a second trip a week or so after 60k service and we've had the occasional strange electrical "glitch" from time to time.
Thoughts?


