‘20 C43 sedan - down on power - no codes . . .
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'20 GLC300 SUV
(9/3 Update) ‘20 C43 sedan - down on power - no codes . . .
Have had my ‘20 C43 since late February. It replaced my ‘18, which was taken back because a myriad of issues.
Anyway, new car has been great. With the pandemic, I’ve been working from home. Consequently, the car only has 637 miles. I go out and drive about 40 minutes once per week, and mostly just cruise in C for purposes of the break-in, and also because I find myself doing highway driving to make the “Starter Battery Critical” notification go away.
I drove a family member’s 2019 E450 the other day, and right away, despite the car being heavier and slightly down on power, it felt substantially punchier/harder pulling than my new C43.
I decide to pull up the Engine Data menu when driving the C43 today, and after warming up the oil/transmission, I do various pulls from a dig and from a roll.
I can’t get the data for horsepower over 267. Even when burying the pedal through the floorboard. Torque I was able to hit 365. Tried accelerating in all modes (not that it should make a difference) - C, S+, etc.
Most of the time I can’t get the horsepower over 200 at WOT, and it never gets above like 20 when cruising around with light throttle.
Boost gauge is showing nearly to the maximum. No codes whatsoever.
Also, despite driving for over 2 hours in the past 3 days, my 12V starter battery is STILL not charged, and the charge is so low that the car won’t give me standby mode as an option.
Related? Also, any thoughts generally?
It was easy to get into the 300+ hp range via Engine Data on my ‘18.
Anyway, new car has been great. With the pandemic, I’ve been working from home. Consequently, the car only has 637 miles. I go out and drive about 40 minutes once per week, and mostly just cruise in C for purposes of the break-in, and also because I find myself doing highway driving to make the “Starter Battery Critical” notification go away.
I drove a family member’s 2019 E450 the other day, and right away, despite the car being heavier and slightly down on power, it felt substantially punchier/harder pulling than my new C43.
I decide to pull up the Engine Data menu when driving the C43 today, and after warming up the oil/transmission, I do various pulls from a dig and from a roll.
I can’t get the data for horsepower over 267. Even when burying the pedal through the floorboard. Torque I was able to hit 365. Tried accelerating in all modes (not that it should make a difference) - C, S+, etc.
Most of the time I can’t get the horsepower over 200 at WOT, and it never gets above like 20 when cruising around with light throttle.
Boost gauge is showing nearly to the maximum. No codes whatsoever.
Also, despite driving for over 2 hours in the past 3 days, my 12V starter battery is STILL not charged, and the charge is so low that the car won’t give me standby mode as an option.
Related? Also, any thoughts generally?
It was easy to get into the 300+ hp range via Engine Data on my ‘18.
Last edited by zibby43; Sep 3, 2020 at 05:44 PM.
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I just got home from the drive in question. So not yet. Thanks for the reply, btw.
Curious that I’m hitting 365 for the torque, but breaking 200 horsepower is nearly impossible.
Do I need to pop off the engine cover here and look for loose connections? I don’t have any diagnostic tools at my house.
Curious that I’m hitting 365 for the torque, but breaking 200 horsepower is nearly impossible.
Do I need to pop off the engine cover here and look for loose connections? I don’t have any diagnostic tools at my house.
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C43
I just got home from the drive in question. So not yet. Thanks for the reply, btw.
Curious that I’m hitting 365 for the torque, but breaking 200 horsepower is nearly impossible.
Do I need to pop off the engine cover here and look for loose connections? I don’t have any diagnostic tools at my house.
Curious that I’m hitting 365 for the torque, but breaking 200 horsepower is nearly impossible.
Do I need to pop off the engine cover here and look for loose connections? I don’t have any diagnostic tools at my house.
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Is it unusual that the torque value seems about right, but the horsepower seems low?
Any thoughts on the battery and whether that is a sign of anything? Thanks again.
Edit: While the dealer trip seems inevitable, my previous car lived at the dealership, and my eye is twitching just thinking about all this starting up again.
Sigh.
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C43
Appreciate the feedback. Will check tonight.
Is it unusual that the torque value seems about right, but the horsepower seems low?
Any thoughts on the battery and whether that is a sign of anything? Thanks again.
Edit: While the dealer trip seems inevitable, my previous car lived at the dealership, and my eye is twitching just thinking about all this starting up again.
Sigh.
Is it unusual that the torque value seems about right, but the horsepower seems low?
Any thoughts on the battery and whether that is a sign of anything? Thanks again.
Edit: While the dealer trip seems inevitable, my previous car lived at the dealership, and my eye is twitching just thinking about all this starting up again.
Sigh.
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Nah, the battery would have nothing to do with this. Yes, it is unusual for the the TQ to be fine but the HP to be so low (though I do not necessarily trust the on-board Merc read out). Sucks you had a bad first experience, but I hope this issue is quickly and easily resolved!
I found an old thread on the subject and a post in there mirrors my symptoms almost identically. Poster never followed up, but looks like a dealer visit is likely.
EDIT:
Think the battery issue may be related.
Found this in a 63 thread.
”So to shorten the story, after they "reprogrammed" the ECU/ME, all my power is back. He said he has seen many 63s with this same issue due to low voltage tripping the "limp" mode and said once that fault code is registered, it has to be removed/reprogrammed to have it reset.”
My battery getting low several times may have triggered a limp mode that I cannot reset.
Last edited by zibby43; Aug 29, 2020 at 08:10 PM.
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Yeah, no loose connections or anything weird.
I’m guessing all the Starter Battery Critical/12V battery messages I got tripped a low voltage code in the computer. This low voltage code then triggers a soft limp mode.
Once it’s there, it has to be cleared by the dealer (only identifiable with Xentry) and everything needs to be reset.
I would’ve never thought to suspect the battery being related, but the boost bar definitely behaves as normal.
I’m guessing all the Starter Battery Critical/12V battery messages I got tripped a low voltage code in the computer. This low voltage code then triggers a soft limp mode.
Once it’s there, it has to be cleared by the dealer (only identifiable with Xentry) and everything needs to be reset.
I would’ve never thought to suspect the battery being related, but the boost bar definitely behaves as normal.
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C43
Yeah, no loose connections or anything weird.
I’m guessing all the Starter Battery Critical/12V battery messages I got tripped a low voltage code in the computer. This low voltage code then triggers a soft limp mode.
Once it’s there, it has to be cleared by the dealer (only identifiable with Xentry) and everything needs to be reset.
I would’ve never thought to suspect the battery being related, but the boost bar definitely behaves as normal.
I’m guessing all the Starter Battery Critical/12V battery messages I got tripped a low voltage code in the computer. This low voltage code then triggers a soft limp mode.
Once it’s there, it has to be cleared by the dealer (only identifiable with Xentry) and everything needs to be reset.
I would’ve never thought to suspect the battery being related, but the boost bar definitely behaves as normal.
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After having the chance to do extensive reading on the issue, my issue mirrors that of several C63/C63 S owners.
The voltage got so low recently that my Mercedes Me app went haywire (had a thread on that a few weeks ago), indicating that my engine was ON when it wasn't. Multiple "Starter Battery Critical" messages. And now, no matter how much driving I do, I can't get the charge to "Fully Charged," nor can I get it high enough to put the car in Standby Mode.
That has triggered a low voltage code (that I can't see without Xentry) that needs to be cleared. Then I'll need a full reset of all computer systems. After that, I'm going to have the dealer address the battery, so I don't repeat this issue.
What's frustrating is that this low voltage condition (and subsequent "soft" limp mode) can even occur, completely unbeknownst to the driver. If it weren't for my butt dyno, I'd still be driving around 120+ horsepower down for the next 400 miles (as I have been driving mostly in C during break-in).
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C43
What's frustrating is that this low voltage condition (and subsequent "soft" limp mode) can even occur, completely unbeknownst to the driver. If it weren't for my butt dyno, I'd still be driving around 120+ horsepower down for the next 400 miles (as I have been driving mostly in C during break-in).
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Yeah, that's the worst part that you didn't even get any warnings or notifications. I hope it's just a battery issue and getting that replaced will fix it. However, there are cases where if the battery wont charge after a 30 minute or so drive, then it also might be an alternator issue.
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I have noticed that the Start/Stop green light comes on by default every time I start the car, but since turning it off is one of the first things I do before setting off, I don’t check to see if it’ll actually turn the motor off at a stop.
Did your green indicator light come on?
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Going into the dealer’s shop on Thursday.
So far I’ve mentioned the low voltage code, the battery not charging (possible alternator issue), etc.
Since I’m making boost, that should about cover it. I haven’t driven a ton, but I know I’ve done enough that I should’ve never had any of these issues.
So far I’ve mentioned the low voltage code, the battery not charging (possible alternator issue), etc.
Since I’m making boost, that should about cover it. I haven’t driven a ton, but I know I’ve done enough that I should’ve never had any of these issues.
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Thanks for the suggestion. I’ll try that.
I have noticed that the Start/Stop green light comes on by default every time I start the car, but since turning it off is one of the first things I do before setting off, I don’t check to see if it’ll actually turn the motor off at a stop.
Did your green indicator light come on?
I have noticed that the Start/Stop green light comes on by default every time I start the car, but since turning it off is one of the first things I do before setting off, I don’t check to see if it’ll actually turn the motor off at a stop.
Did your green indicator light come on?
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Going to need them to look for the low voltage code, clear it, reset all computers on the car to eradicate the soft limp mode, and then address the battery (and possibly alternator, if there's an issue there too).
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Car went into the dealer this morning at 8:30. I told them I suspected a faulty battery + soft limp mode as a result of a stored low voltage code.
Got an update this afternoon that the car would have to stay overnight, as the dealer needs to do a cold start check in the AM. They replaced the battery (which was faulty), and also reset both the ECU and TCU (as I also suspected was necessary) to clear the low voltage code and hopefully restore full power.
If anyone has any loss of power issues and there are no loose connections/you're making boost, you could have a bad battery and a low voltage code, which triggers a soft limp mode that only your butt dyno + the Engine Data screen can help to confirm. Or, if you have Xentry lol.
Crazy that this problem can happen without triggering any visible CELs beyond a 12V battery warning on the gauge cluster, which will go away after a drive.
Got an update this afternoon that the car would have to stay overnight, as the dealer needs to do a cold start check in the AM. They replaced the battery (which was faulty), and also reset both the ECU and TCU (as I also suspected was necessary) to clear the low voltage code and hopefully restore full power.
If anyone has any loss of power issues and there are no loose connections/you're making boost, you could have a bad battery and a low voltage code, which triggers a soft limp mode that only your butt dyno + the Engine Data screen can help to confirm. Or, if you have Xentry lol.
Crazy that this problem can happen without triggering any visible CELs beyond a 12V battery warning on the gauge cluster, which will go away after a drive.
Last edited by zibby43; Sep 3, 2020 at 05:54 PM.
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They should the very least give you a good loaner for how loyal and patient you are while they get things sorted out that should seriously had been sorted out already. W205 was a late 2014 (MY15) car, it is 2020, 5 years and they can't get anything right?
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=_= what the hell, so sorry for the trouble you are dealing with your new car already. What the hell, MB? Hopefully things get fixed as fast as possible. This pandemic already made it so hard for you as you can't even properly enjoy your car cuz of it and now that the restrictions are slowly lifted you still can't enjoy your car because of things like these.
They should the very least give you a good loaner for how loyal and patient you are while they get things sorted out that should seriously had been sorted out already. W205 was a late 2014 (MY15) car, it is 2020, 5 years and they can't get anything right?
They should the very least give you a good loaner for how loyal and patient you are while they get things sorted out that should seriously had been sorted out already. W205 was a late 2014 (MY15) car, it is 2020, 5 years and they can't get anything right?
Haha thank you for the support my friend. Pour one out for my '20 C43 lol. Not looking great at the moment, but I'm used to it (sadly) at this point.
I don't have ANY loaner at this point, which is disappointing. I dropped it off Thursday AM knowing there was no loaner available that day because I thought this was going to be a quick, straightforward fix (mostly because I troubleshooted the problem on my own before taking it in). But when they broke the bad news today, I asked them for a loaner so I wouldn't be without a car on the weekend.
They didn't even respond to my request. I've been very patient on this matter so far, but that ends Monday.
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Hey buddy! How goes it?
Haha thank you for the support my friend. Pour one out for my '20 C43 lol. Not looking great at the moment, but I'm used to it (sadly) at this point.
I don't have ANY loaner at this point, which is disappointing. I dropped it off Thursday AM knowing there was no loaner available that day because I thought this was going to be a quick, straightforward fix (mostly because I troubleshooted the problem on my own before taking it in). But when they broke the bad news today, I asked them for a loaner so I wouldn't be without a car on the weekend.
They didn't even respond to my request. I've been very patient on this matter so far, but that ends Monday.
Haha thank you for the support my friend. Pour one out for my '20 C43 lol. Not looking great at the moment, but I'm used to it (sadly) at this point.
I don't have ANY loaner at this point, which is disappointing. I dropped it off Thursday AM knowing there was no loaner available that day because I thought this was going to be a quick, straightforward fix (mostly because I troubleshooted the problem on my own before taking it in). But when they broke the bad news today, I asked them for a loaner so I wouldn't be without a car on the weekend.
They didn't even respond to my request. I've been very patient on this matter so far, but that ends Monday.
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I'll update this thread daily so it can serve as a resource in the future for anyone else that runs into this problem.
Drove a family member's '20 C300 loaner today and it felt like a Ferrari 488 in comparison to how my C43 felt before I took it in. It was easily hitting 250+ horsepower in the Engine Data screen, whereas mine mostly topped out between 197-230ish.
