cpisog

Hey All,

I have a 2019 Mercedes C43 sedan and its not showing the full 385 HP or getting close to 300+ HP on the engine data gauge. When punching the throttle I am only getting around 200-250HP max. The boost however does go towards the max and does hold.

As a note, the car was making the infamous honking/goose squak in the engine bay a few weeks ago and I had both the boost pressure transducer valve and vacuum check valve replaced, which resolved the noise and helped resolve previous boost issues, however, I am still not able to get close to the high HP numbers (+300HP) in sport + mode.

After some assessment there are many folks on this forum who experienced similar issues, which lead to a many different of solutions:
-Boost leak (however for myself the boost holds and no leak noise)
-Wheel sensor
-Limp mode (Can the car throw a secondary fault if boost transducer was failing which could explain limp mode?)

Has anyone experienced this and any recommendations for a solution to regain HP?

I appreciate all your knowledge and support!

W205C43PFL

It does indeed sound like soft limp mode, any codes reported?

cpisog

Hey,

Thanks for replying! Much appreciated.

No idea if there any fault codes as I do not have an OBD reader. I am thinking of grabbing a relatively cheap one or going to my local Autozone for a diagnosis before taking it over to my local MB indy.

No CEL either, just the symptoms I mentioned before.

Nonethless, after reading through many posts on here and other forums regarding similar symptoms, all signs lead to soft limp mode given I recently had my boost pressure transducer failure, which could limit the air intake and trigger a secondary fault code.

Hoping that this is it and my local MB indy can reset software if they have the possibility and reach similar conclusion. Fingers crossed.

cpisog

Ok just did a preliminary diagnosis and only codes that came up were relating to the ABS (Fault codes: B23AA14 and B23AB14). Both pertain to the left and right brake calipers malfunctioning. I have no light indicating this on my dash (i.e., parking brake yellow note or symbol). Seems odd that this would trigger soft limp mode. Can anyone provide guidance on if this seems possible?

Appriciate your knowledge and support!

W205C43PFL

You're welcome : )

Hmmm you got these codes form AutoZone right? Are their scanners capable in finding MB specific codes?

cpisog

Hey,

Yup Autozone, wouldn’t trust their MB diagnosis so I am taking this with a grain of salt and will be getting a diagnosis from my local MB indy. I just got the diagnosis from Autozone for my sanity.

Nonetheless, just came back from the gym and pushed the car on my way back and here’s what I have noticed so far.

-0-60mpg in around 6.6-7s (also measured with FastR app no dragy) and I only get to about 300-320HP when punching on throttle and going through a few gears (not from the jump or few seconds); and Im unable to even reach around the 350-80s in terms of HP.
-I am unable to get +200HP when in comfort.

All these could be driver excuses but I am sure the car was faster when I first got it and it definitely feels like it has more potential.

I will be updating this post as I get more results for others experiencing similar problems.

Thanks again, really appreciate the conversation and your knowledge!

W205C43PFL

​​​​​​I see, hopefully us forum members can figure it out for you so you can enjoy the car again in whole. Did you happen to kickdown (pedal beyond resistance, click at the end) and still not get full horsepower? You may consider getting a scanner like the Launch CReader Elite Benz V2.0 that other forum members recommend on amazon to scan MB specific codes. It also enables some sort of variant coding as well as a plus.

cpisog

Hey,

I just purchased this from amazon online and should be getting it within the next day. I will try doing a self diagnosis with this tool and hopefully get a more conclusive understand as to what it going on before bringing the car in.

Regarding the click point during throttle, I am pushing the throttle to the floor beyond resistance when attempting to make a 0-60 run.

Thank you for your guidance on the scanner tool and really appreciate the support. I am hopeful to get the car back to how it orginally performed.

W205C43PFL

Sounds good, keep us posted.

cpisog

Hey all,

I just recieved my Launch Creader (thanks for the recommendation W205C43PFL) and performed a self diagnosis.

Please find the faults observed in images attached below.

It seems that none of these codes would lead to or trigger the symptoms that I am noticing with my car (i.e., not being able to hit high 300HP+).





Nonetheless, I will be taking the car into my local MB indy for my sanity.

Regarding the issues I am noticing:
-In Comfort, I never can get 300s in HP and usually stay within 100-180HP when punching the throttle
-Can hit +300-350 after a few moments of punching the throttle in S+

Also, for confirmation, in regards to some of the codes identified; would “stored refer to faults observed in the past and are not active currently”, while “stored and current” are actual current faults.

I appreciate your time and support!

trigital

Indeed the “stored and current” are actual current faults. Being about ESP I would make a quick appointment to dealer ( if you trust Launch). ESP is vey important not only for your safety but for the power as well. Engine always wait specific information from ESP ( tires slippery start, lateral and transversal inclination, etc. ) for releasing the full power.

Also Engine will never release full power if Steering wheel it is not in straight position, Same for firsts and second gear,

Launch is not a legit scanner. The same is Xentry on Aliexpress or ebay or like any other sources beside MBUSA. But Xentry besides the legit/nonlegit part is the most complex and trustful diagnosis software ever created.

And Xentry ( with fake activation ) cost USD100 or something

W205C43PFL

I mentioned Launch because it was tested and recommended by forum members here that had more advanced scanners that cost thousands and the full suite systems including XENTRY including those that they purchased from Peter, yes it is not a replacement for XENTRY no doubt about that but it is the more capable scanners out there that is pocket size at a fraction of the cost.

I certainly do not recommend the fake XENTRY stuff online (personally) but if it works for you, that is great : )

OP, those are indeed a lot of codes, some are voltage related, I am curious, how old is the battery? What about the aux battery?

cpisog

Hey,

I am unaware if the batteries have ever been replaced (Ive only had the car for a year and am the second owner).

Scanner reads the battery at 12.3V with ignition off and 13.8V with ignition on. I believe these are within range?

cpisog

I will be bringing my car to a local MB indy for regular service, so I plan to bring these concerns regarding ABS. I am confused why the ABS light is not displayed on my dash yet these secondary codes are popping up.

Thanks for the support and information!

trigital

Although is off topic here, there is no any version of Xentry legit beside the MBUSA or MBEU based on subscription.

Any other solutions are not legit at all, but mostly do the job perfectly on a non-professional environment.

And Xentry legit or not can be used with a 20$ interface.

W205C43PFL

Hmmm, I thought fully charged it should be at 14.6V when ignition on? I could be wrong though.

W205C43PFL

Yes, that is correct.

cpisog

Hey,

Did some more research based on the codes that were observed:
-With regards to “U012287”, another poster had similar symptoms that I have encountered (i.e., low HP boost okay in C mode); the poster also noted ESP module being disconnected which indicates fault codes that are similar to mine (i.e., B23AA14 and B23AB14)
>>>Even after having the drive unit and ESP module disconnected/reconnected although the fault codes disappeared; poster stated he was not getting the rated HP: HOWEVER, it seems in manual mode with a tech in the car he was able to get the rated HP
LINK TO POST: https://mbworld.org/forums/c450-c43-...o-codes-3.html
LINK TO ANOTHER POST: https://mbworld.org/articles/mercede...oss-explained/

Given this, I think I will reach out to my local MB indy given the observations that I was able to gather to request batteries to be replaced and “reprogramming” of ECU/ME.

I will definitely give you all an update after consulting with local MB indy. BIG SHOUTOUT to W205C43PFL for his knowledge and conversation to help me drive down to an adequate root cause.