philly_tee

Hi there,

I apologize in advanced if this has been asked and resolved - I have tried searching but haven't found any concrete answers.

I am new to the forum and Mercedes, I just traded my 335is in for a 2015 C400 (needed 4 doors). I got the "Collision Prevention Assist + Inoperable" yesterday and my car went into what I would think is "limp mode". I am now scouring the forums which I noticed are not as extensive as E90post but anyways I saw that this seems to be a common issue (or was). More importantly I have not seen too many recent posts which leads me to believe that this has been resolved - has this issue been resolved? What was the solution? My car does not have a warranty and its sitting at Mercedes now! I can only imagine how much this will all cost. Ultimately though, I cant have this happen while on the highway with my daughter so I just need to have it resolved properly!

Thanks in advanced for whatever info you can provide.

GreekUPS

Try these threads for some info:

https://mbworld.org/forums/c-class-w...ive-error.html

https://mbworld.org/forums/c-class-w...operative.html

philly_tee

Thanks for the threads!

I have looked at both of those before and haven't found my answer, maybe this means there is no resolution or actual fix.

In both of the threads people mention opening a case with MBUSA and trying to get them to buy it back or replacing sensors, update software etc... In the latter of the two some people mention the problems still coming back after updates or replacing sensors.

Does this actually mean there is no concrete solution in 2019?

fabbrisd1

Well .... right now you have (2) separate problems at the dealer waiting for diagnosis...

On the Mercedes C400 you just traded for .... are we to assume to got your C400 from other than a MB dealer - or did you purchase non-Certified from a MB dealer ?

The reason I ask is to find out if you have Mercedes Certified Warranty in place or not....

The two separate problems that you outlined..

1. Limp Home Mode - which has nothing to do with Collision Prevention Assist Plus - and frankly that's the worry note. Under what "situation" did this appear ?

2. Collision Prevention Assist Plus "inactive" warning light - which can be a # of different smaller things..

philly_tee

Thank you for the reply.

My car was bought from a non Mercedes dealership I have no Mercedes Certified Warranty in place.

1 - I exited the hwy and a km after the exit ramp I hit a red light. I started to drive and probably 10 meters after the intersection my car lost power completely. I got a sign on the dash saying Collision Prevention Assist inactive and under that it said inoperable. I pulled over to the side of the road and the car crawled there. At this point I did not know what to do, so I put it in park and turned off the car/restarted it. Everything was normal and it drove off perfectly fine. Today on my way to the dealership it was normal as well.


2 - That came on when the car lost all of its power and I had to pull over to the side.

fabbrisd1

If the engine stalled - then yes, you would get a Collision-Preventationb-Assist inactive light at that time.

In pulling away from a stoplight - car stalls/to-limp-home mode - the good news is that it restarted and has been driving normally since.

There "should" be some stored codes - without those codes here in the US we would suspect fuel-filter/air-filter-instake/injection as the source of the stall - if there are not any stored codes then it comes down to guess work.

Not know where you are located - I would dose the tank with 1/2 bottle Stabil Marine Fuel Stabilizer (Blue bottle - here in the US about USD$9) to clean up the fuel tank and injection system - based on miles/condition you might consider fuel-filter/air-filter - and if approaching 50K miles fresh OE-spec sparkplugs.

Keep the beat !

philly_tee

Thanks! I appreciate the reply again.

I am located in Canada - I got a call from the dealership and they said that they scanned and no codes were found, nothing to replace. They said they updated the software and that should fix the issue.

I asked if this was something they had seen before and he said yes. This software update has resolved this issue in the past.

I drove home and it was fine so I am kind of left at that for now. I really hope this doesn’t happen on the highway and especially with my 6month old in there.

Tirgoman

One thing I've found works now that the cars are moving computers is when I get a message on the dash or display is to take a picture. Yes, most are one time and if you stop, turn the car off the car and open the door, wait about 15 seconds, close the door and then re-start the car. But if it continues you have something to show the dealer the message/issue and in spite of them saying there are no codes you can show them proof. One picture is worth a whole story.

jlr82

Very good advice... I had a situation where one of my previous cars would indicate that there was a problem with the rear brake light, but after pressing any buttons you couldn't get the message to come back. After a few trips to the dealer and finally snapping a photo they looked into it enough and found a problem with the wiring harness, which eventually became a recalled item several months later. Without the photo there was not enough proof for them to look very deep at the issue.

CJG

How can one tell if the CPA is even working? I’ve tried coming up on slow cars quickly and nothing seems to happen. When I had a loaner I accelerated behind a car from a stop light apparently too close/quickly and it beeped. Mine has never done that.

GreekUPS

I’ve had the warning light and sound go off multiple times but it has never applied the brakes for me.

philly_tee

Thanks for all the help!

So far since the update it seems to be fine - will update again in a month if it is still fine. Should it happen again, I will update ASAP.

Regarding the car braking for you and just the lights going off, I believe there is Collision prevention assist and Collision prevention assist plus. (I could be wrong, new to MB)

Collision Prevention Assist - Alarms you when getting to close (Lights, image, sounds, beeps)

Collision Prevention Assist Plus - Alarms you when getting to close (Lights, image, sounds, beeps) + Autonomous Braking

fabbrisd1

CPS is alert is designed as a additional safety measure in around-town/city/non-freeway to alert you of possible collision in time for your to look/react to that situation as COLLISION AVOIDANCE SYSTEM.

CPS+ is a COLLISION REDUCTION system that provides full emergency braking autonomously if it determines there will be a collision AND if you have not applied any braking at all. Once the driver has applies any braking at all - the "+" is deactivated - however Brake Assist is active/working.

Ripkord

Man, I wish I had better news for you.

I bought a 2015 C-class at the end of december and this issue plagued me. Had it in to get it fixed under warranty three times, maybe four - I lost track.

Anyway they were never able to find an error code and it happened so randomly I didnt want to leave the car with the dealer until they could 'generate' the error themselves.

Fortunately for me, the dealer offered to exchange the vehicle, well they took it back after 60+ days, paid off the finance, and let me take a new deal.

I wish this story had a happier ending for people affected by this issue! Credit to the MB dealer in Glasgow though, they were awesome.

philly_tee

Well, it happened again this morning - this time it happened twice on my drive to work. 5 minutes into drive I stop at traffic light and it happens, car is drive-able but slow. I recorded the entire thing on my cell phone as @Tirgoman suggested. I turned the car off then back on and it was all gone. I was happy that I had the footage and continued to drive to work, as I got to work it happened yet again. I took another video and without turning the car off I called MB. I started to drive there and the service advisor who dealt with the car on Monday said to bring it in.

When I got there he said something about salt and corrosion behind the gas pedal which would result in a loss of power and then cause CEL as well as all the other alerts. They gave me a CLA loaner and now I am like WTF did I buy? I've had the car for 2 weeks and this sh*t is happening, I have no warranty so I am pretty concerned as I don't even think Mercedes would buy it from me. I tried researching issues with the car before I bought it but did not see any of this at all. This is such a depressing situation, especially after hearing what @Ripkord has said.

Will MB offer to exchange my vehicle if I did not buy it from MB? (Pretty ludicrous ask I know)

Ripkord

It would depend on the local law and how you purchased the car. In the UK at least, you have 30 days in which you can effectively hand the car back if its not fit for purpose, the finance agreement is essentially cancelled and you get back your deposit etc.
In this case I think you have to give the dealer one chance to fix it. If this doesn't apply to you, you could try to reason with the dealer about exchanging it for another car, but I don't know what legal backing you have if any.

If you don't get any joy there you could appeal to MB and see what they can do. I'm sure they are aware of the issue so there might be some kind of resolution.

Good luck buddy.

philly_tee

Thanks @Ripkord

They are doing some work now so I am going to see how that goes.

I have no warranty but they said they would cover parts and I take labour. Should be ready to pick up today - will call me this afternoon.

Thanks for all the help everyone - I will update again asap.

Tirgoman

Take a deep breath, the service advisor could be right, the gas pedal is indeed electronic, so maybe water and salt got into the electronics as he said. The fault should be recorded when they plug into the OBD II connector. Not sure where you are but this is not a big deal and you should know soon. 😁

philly_tee

Thanks for the positivity @Tirgoman - I do appreciate it.

Im here in Toronto, Canada - Lots of road salt used here. I do remember having issues with my BMW 335 after having it detailed. The soaked the pedal sensor and I lost some acceleration here and there, but it never threw codes or Christmas lights on the dash like this. I do hope that this fixes these issues - thanks again!

Mercedes_300

Hello! - Cross posted, but I see we have the same issues....

I have a c300 4matic 2015 with 91K miles on it. With the exact same issues happening with the "Collision Prevention Assist Plus Inoperative" along with the cruise control inoperable when this message pops up and the traction control symbol is illumined yellow. I then lose all power to the vehicle, it enters a "limp mode" if you call it that. Driving 75 down a highway the car will randomly activate this warning and you lose all control to accelerate. You have to quickly pull over and restart the car, the message then disappears and all is back to normal. *THIS has only started happening once a new battery was installed by MB dealer last week, the day after driving down a freeway and has happened 5-6 times over 7 days. Could you imagine having a family in the car and losing all power in the center of a freeway?

Immediately called MB service advisor (when it first happened) who told me to wash the car as it's winter here in Minnesota. Which seemed valid as sensors can do crazy stuff when dirty... Did that, the next time I started the car drove it for 30 seconds, same issue. Inoperative warnings come up and lose the power to accelerate. There is NO check engine light on.

So I dropped it off at Mercedes, thinking they installed the battery wrong and needs a software update. They came back with many fault codes, however they singled out the Thermostat? P059700. HERE is the KICKER - The tech then sent a $1,000 credit from Mercedes to fix this??! Seems quite odd to me, they didn't give me credit for he $1,600 crankcase value I replaced last summer.. Anyhow They want over 2K to fix the Thermostat, claiming low temperature of cooling system is throwing off codes and reason it's throwing the collision assist inoperative warning and limp mode. BUT with no check engine light? I've read all of the forums containing to this issue and not one has related this to the thermostat..

A week ago the battery was changed and a service tech did an inspection. They found all levels normal and the car in "great" condition.... Now not even a week later they did another inspection today and found my oil to be overfilled, the wanted a b service, wipes replaced and this thermostat to correct the issue??? I have a hard time believing them that the thermostat could cause collision and cruse control warnings..

Any insight would be great. What should I do? Similar issues - sure looks like it!

philly_tee

MB ended up fixing my car with a software update. The first update didn’t work as it came back after a few days but the second time they updated it (knock of wood) I have not seen it back.

Let me try to find the invoice and see if there’s any info there that I can share with you. I now have a new issue, auxiliary battery malfunction, also my drivers door creaks when closing it. I got it fixed less then a year ago and it’s back again.

I think the cars gonna go this summer, tbh

W205CClass

Can you please share invoice or what update it was so I can do it.