Hello,

Ive been having a nightmare of a time with my 2016 C63s Cabriolet, it’s currently at 90,000km’s, and has been extremely well looked after, recently had the transmission serviced, and the previous owner took care of all the needed rear differential oil changes as it’s not yet due for one again just yet.

over the last 9-10 months this irritating error has popped up multiple times at random, sometimes it would pop up multiple times in a day at random, other times wouldn’t show up for months. In the last three months or so it’s become more common, but again, hasn’t been very regular. In the three days though, it’s become an everyday occurrence, the first two days it was a few times, and I’d be able to clear it ONCE with my iCarSoft MB scan tool, allowing me to properly enjoy the car without the god awful “limp mode” feeling with the accelerator and the rear diff not working, jerky acceleration etc.

today though, it’s now become a total nightmare. It will. Not. Bugger off. I’ve had three places check it already, including the Mercedes dealer. They could not find anything wrong with it.

the most recent place was a diff & transmission specialist, however I was in the process of trading the car in, and I am skeptical about this mechanics diagnosis as he simply plugged it up to his scan tool and was able to tell all of this based off of what came up on his scan tool, if this is possible, please let me know…

he told me the rear diff isn’t locking because it’s “sheared”, so it’s spinning “freely” and isn’t locking, causing this error to pop up. Weird thing is, once the error goes away on its own, the car drives completely fine, when the error is on, obviously it drives like crap. But if it was “sheared” and needing to be completely replaced, wouldn’t it not drive properly AT ALL?

the dealer was told by this mechanic I was reading the car in about the rear diff needing to be replaced so they wanted to reduce 7k out of the trade in price, naturally, I’m skeptical if this is even true, and it isn’t a tactic just to low ball the absolute crap out of me.

today, using my iCarSoft scan tool, I’ve had to manually clear the codes and restart the car around 6-7 times each time I restart the car after stopping it, it’s become really worrying now, otherwise, it simply drives like garbage.

has anybody else had luck with a possible software update, actuator replacement, or finding parts for these rear differentials as I’ve been told they don’t have parts and basically you need to replace the entire diff if anything goes wrong…

it just seems like an electrical issue as it comes and goes, apart from today, and one of the errors is “rear differential has a malfunction, the signal is not present code: P1C4E31, second code is: P1C4E00 - The differential Lock on the rear axle has a malfunction.

any help would be greatly appreciated.

 

The diff is not sheared. It's an electronic locking diff with a clutch. This is a known issue with the early diffs in the 2016 models. 9 out of 10 times it's a faulty actuator and needs to be replaced. Do a search. This has been discussed before. Some who have tuned their cars managed to shred the diff, but most others it's just the actuator that failed. Yes, dealerships tell you to replace the whole thing. Surprised that a specialist shop gave you no better diagnosis.

 

Well I replaced the DC motor, still coming up. So it hasn’t solved the issue, looks like a new diff.