Hey guys!

I have got some issues lately with my E coupe. My car enters limp mode without any errors suddenly, which is a bit strange. If I turn it off and on it goes back to normal, but for a split second it shows the ESP/ABS unavailable error, and I mean it is so quick I had to take a video to see exactly which error it was. No lights in the dash, no nothing.

Now I have seen some patterns: It most frequently appears when the engine is cold and I accelerate moderately up the hill. It also happens when cruising on the highway, and you can’t really notice the limp mode if you don’t kickdown and see that it doesn’t want to take off (Again, no errors whatsoever). Random instances otherwise, or at least nothing that seems like a pattern.

It doesn’t seem to come back to normal after any period of time. I have tried that trick where you slowly steer while driving but had no success.

Battery is quite old but the voltage is fine. Any other ideas? Thanks.

PS. 2010 Model, 7-GTronic, 350CDI 231hp.

 

I would swap out that battery. I'm sure your car is very different than mine but a low battery caused me all kinds of weird issues. Not real issues, meaning the low battery didn't directly cause it, but the ECU is apparently playing games and sees the voltage is low on or before start goes into "F with you mode". I can only imagine it's to get you to go to the dealer and spend $ on troubleshooting and parts. And it does, at least my car, watches the voltage before and during start so I know it's capable of it.
First thing I lost was the Eco start/stop function. Then I believe it was the backup camera? The biggie was it would start missing randomly at idle, then a week or more later at higher rpm, so I'd simply drive in a lower gear. Then it would do it at that rpm and so on.
Running voltage was perfectly fine. Static voltage was only a little low, nothing I'd normally worry about other than I know I'll need a new batt in a year or two.
I replaced the batt, problem solved, instantly.
I also get a random dash light, which I think is ESP? I forget, but it turns out it's triggered by reflections from reflective road signs, apparently. So if you get one in the same spot in the road all the time, note that and any signs or reflective crap. Otherwise I get all kinds of codes all the time, including ESP/ABS, but usually it's says communication lost. I've seen unavailable too, but to be honest I just ignore them. I don't think I've had a limp mode, at least not in >10years? I get a different kind of bs now and then, apparently called an "ECU reset", but not limp. But then I've had limp disabled for the past 8 months so who knows, but I doubt it.
So battery #1, imo. You gotta replace it soon anyway, might as well get it outta the way and see if it fixes it it.

 

Quick update:

The battery apparently is the original battery, which is incredible. It shows 12-12.1V UB in the dashboard so that I will certainly replace. While running at idle it goes up to 14.2 so the alternator seems to be fine.

I found out a steering angle reset would actually solve these weird kind of issues with limp mode and ESP, so I went ahead and did it. No problems whatsoever since then, and the car seems to feel a bit better overall in terms of gear changing and overall smoothness. I will keep you updated just in case this wasn’t the solution.

Thanks for your replies guys!

 

Interesting, I've never heard that. I will store it in my memory banks for future use, thanks.
My batt voltage was higher than that when my car started acting weird, so I guess they weren't F'ing with people back in 2010. And world record batt life, unless it's actually the 2nd one, then typical life span The MB batts are top of the line though

 

345K kilometers on the clock, mostly Austrian highways. Considering it’s pretty cold i’d say it is actually a pretty good battery.

I did 500km since the reset, no issues whatsoever, and the car is flying. Strange issue and even stranger solution, but I am glad I didn’t spend any penny solving it.