Spazdoc

I was test driving a 2014 C63 today, and about 15 minutes into it on the highway, the car had the statement "Pre-Safe Functions Limited" and basically acted like it was stuck in neutral. I was on the highway and coasted off the highway, but neither I nor the salesman could get the car to work despite restarting the car several times. Everything aside from the blind spot and parking distance was working, and the check engine light was on.

I was driving in M mode, shifting between 3-4 gear at 60-80 mph. Did not redline at all. Car was warmed from about idle and about 15 mins of driving.

I searched online and this seems like a rare event, and I did not see anyone post with a C63 from a brief search. I have seen limp mode in my BMW 335i, but the C63 did nothing. Does anyone know if this a major problem for this car?

Is this a sign that I should try the other C63 at the dealer (a 507 Edition)?

whoover

That's a malfunction of the Distronic Plus radar system, which can stop the car to avoid an accident as well as do the usual tracking the speed of cars in front of you. It's a rare event because most C63's don't have Distronic. It's expensive ($3,000 extra) and is made for drivers who appreciate the car doing as much of the driving as possible, which is not your average AMG owner. I think of it as cruise control from hell.

It's also complicated. My advice is to not give up on C63 but avoid Distronic Plus like the plague.

bjonesmd

I really enjoy Dystronic Plus. I don't use it very much but my AMG is a daily driver with a Monday morning commute in highway traffic. I can set the CC on a reasonable speed and then relax without having to constantly adjust for the flow of traffic. It is almost seamless in that application. The Lane Keeping is hit/miss, it rarely engages. When it is not in use, there is no intrusion on the driving experience.

I have had no problems with it at all, only 3K miles but nothing in that time.

149max

Same.

I love distronic plus. It's an amazing feature.

Don't use it all the time. But when I do I'm always impressed. Definitely worth the money.

Spazdoc

So are you able to disengage it in this situation? We were stranded and could not figure it out. Mind you, I have not owned a Mercedes and not familiar with navigating the settings (mother has an E55, but that has older electronics).

I would not want this to happen when I am hours from home.

bjonesmd

Well, I have never had any issues, but in the settings you can turn off the radar and each of the features such as adaptive cruise control and lane keeping assist. I can't say that would have solved the problem that you experienced, maybe.

I have been reading the forums awhile and this is the first time I have heard of this problem (I have not done a search). You may want to check the technical forums. However keep in mind that only the few with problems will likely post threads. The forums tend to spotlight problems, without a real reference point for frequency of occurence (with some exceptions).

FWIW, I am very happy with Dystronic Plus, I only wish it had more features, such as those available on the E-class.

whoover

Sorry Distronic lovers. I didn't mean any disrespect. Of course different drivers have different likes and dislikes. I obviously was speaking my opinion.

That said, OP, it's clear the system suffered a major failure and it's probably a rare event in itself. It's not something that you would expect can be overridden with a setting. That's because Distronic is tied into the brakes. If it senses you are about to rear end something, it will slam on the brakes for you. Obviously any computer control system that has access to the brakes needs to fail very safely. That's why this particular failure puts the car out of service. Again, it's probably rare. But it's another reason to avoid Distronic IF you don't expect to drive the car with it engaged. My driving style is as manual as is possible (and I've had Distronic on past cars) so I'd consider it an unwanted complication. But you may love it, in which case focusing on it's failure is not the best approach.

rediesel

Distronic is a pretty cool feature. I didn't want it in a sports car as I wish to be engaged to the driving experience, but after trying it out it is amazing.

I get that warning all the time - evrytime I turn stability off. Seriously, turning stability completely off should disable pre-safe functions. I get a big orange warning to that effect everytime.

Distronic won't work when stability is in sport, but the blind-spot and other pre-safe features do.

whoover

Yes, turning off ESP turns off some Pre-safe plus features and you get that message. But that doesn't immobilize the car. This situation was obviously not just that informative message, but because of a Distronic failure.

rediesel

I was answering OP's follow up question.

ESP on all distronic and pre-safe functions
ESP in sport mode turns distronic off and disables some pre-safe
ESP off goes further and turns the vast majority of pre-safe off

Turing off stability (hence distronic and the vast majority of pre-safe) might have helped alleviate the situation, gained insight into the problem and perhaps allowed the car to drive to the dealer

OP - how did the car make it back - tow?

Spazdoc

So we were stuck for about 30-45 mins, and a technician came to scan the car to figure it out on the street. After about 10 mins, they decided to drive us back in the service vehicle and tow the car back.

We were not changing any functions at the time, ESP was on, and the salesman was just playing with the Nav. The salesman and my wife did not realize anything was wrong until we coasted off the highway and I parked the car because the gas had no effect.

507AX

Side note: Is there Dystronic Plus in the 507 edition?

rediesel

Wow I've never experienced anything like that. It must be a sign to go look at the 507. Pretty much guaranteed a better experience after that test drive.

whoover

Distronic Plus is the "Driver Assistance Package" that's available as an option on all versions. It's not standard on any car.

jcfay

I didn't pick up my '14 C63 wanting Distronic, in fact, I wouldn't have selected it as an option if I hadn't just purchased the car I saw and liked and it was already included as a package. That being said, like most here I've enjoyed it and it and the other many safety features available (pre-safe brake, lane assist, etc.) definitely make driving far safer than in cars without. Of course, your story highlights the downside of all of this wonderful tech when it fails it can fully disable the car. I bet the salesperson would give you a sweet deal on that tester now! (Not that you'd want it?... although I'm sure it's an easy fix...).

Greyish99

I Guess this thread is a bit old, but figured id post anyhow. I just bought a W212 2011 E350 CDI 4 matic from a dealer. Car has around 104.000 km, looks brand New. I was happy driving it around for like 10 days. Then one day i got the Message Pre-Safe functions limited, followed by the Lane Assistant, Blind Spot Assistant and Distronic Plus shutting Down. It was raining/snowing at the time, but not a whole lot. After work when i started the car, it was normal again. The next day i was driving on the highway, when all of a sudden it was like the car was in neutral, and i had to make an emergency stop. No messages on the display. I turned the engine off and back on, now i could drive, but the check engine light was on, halfway home same thing happened. Took a litte longer to get the car to act when i put it in drive, but finally got home. I called the dealer, and they sent a towtruck to carry it to their shop. That was yesterday, Guess i have to wait till Monday to see what is going on. During the last couple of days i also had a couple of other odd incidents. I had been in the grocerystore for like 10 minutes, when i came back my alarm was screaming. The other thing was the alarm on the Dashboard (parktronic system?) by the windscreen, it was beeping and lit up everytime a car or lightpole was like 2 or 3 meters away, not normal at all. It stopped after a few minutes. It seems all of this must be caused by some fault in the electric system. Sad to experience this when i spent like 55.000 euros on the car. (Cars are very expensive in Norway)


Anyone have an idea what causes errors like this?


Thanks in advance
Oyvind

PeterUbers

This is just snow blocking the sensors... Not a real problem

Greyish99

There was no snow on the car, it was melting as fast as it hit the car. And the second time when it happened that day, it was'nt raining or snowing at all, the car never had actually snow on it. The next day when the car wouldnt run in "drive" anymore, it was not raining or snowing. Even if it was raining cats and dogs, surely the car shouldnt totally shut down and refuse to run in drive. When this happened on the highway, it most certainly felt like a problem. I guess i will have to wait and see what the dealer says. i don't want a car where i have to look at the weather forecast before i set out to drive.

jcfay

no, this is something else besides something blocking the sensors. Yes, you get the "presafe functions limited" and other stuff if Distronic experiences a malfunction, but that's it. Everything else you describe is unrelated. You definitely need to get it evaluated as that is odd behavior. HTH

Greyish99

Its very odd indeed, not to mention dangerous. I can only imagine if trying to pass a 18 wheeler, and suddenly you have no power, and a car is coming against you. You judge a situation up front before committing to the passing of the long truck, based on the distance to the car coming against you and approx. speed he would have, and the acceleration of your own car.
The dealer has had the car from late Friday afternoon, but probably didnt start working on till yesterday. I will post here any new information i get.

Yu Chem

Hi Greyis99

did you get your car back? do you know what was the issue? I am having similar problems with my 2007 R350 it eventually stalls, engine idle but you can coast.