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I purchased a GLC 300 last year and it’s had a number of electrical issues that the dealer either can’t recreate or can’t find in the cars error registry. Problems range from random warnings about sensor failures to cooling fans randomly reving up and down while the car is off and has been sitting for hours,
to the instrument cluster going to a blank white screen.
has anyone seen these issues before or know of a fix other than a “software reset”?
I purchased a GLC 300 last year and it’s had a number of electrical issues that the dealer either can’t recreate or can’t find in the cars error registry. Problems range from random warnings about sensor failures to cooling fans randomly reving up and down while the car is off and has been sitting for hours,
to the instrument cluster going to a blank white screen.
has anyone seen these issues before or know of a fix other than a “software reset”?
I'm sorry to read about your degraded Mercedes ownership.
This is not too bad until the powertrain quits while in traffic at 70mph
What you've described involves a combination of faults with the ECU on CAN-C and the Cluster on CAN-B...
What's in common is a network gateway rendered unstable by other faulty modules - It is referred troubles such as wet HL Modules or loose something else....
To troubleshoot this further a full scan will confirm what modules are actively faulty.
This maybe a simple fix unless many expensive modules get replaced with little results.
Basic troubleshooting is now your priority. Using an handheld scanner will give you result where Xentry was useless.
I’m not sure I understand the powertrain quitting at 70mph comment though.
As for the other info, it seems like the issues are intermittent and whatever scan tools the dealer is using can’t find a problem. I’m leaning toward something is loose. Thankfully it’s still under warranty with it only being 1 year old.
If they say they can’t find a problem again, it’s staying at the dealership until they do find one.
I’m not sure I understand the powertrain quitting at 70mph comment though.
As for the other info, it seems like the issues are intermittent and whatever scan tools the dealer is using can’t find a problem. I’m leaning toward something is loose. Thankfully it’s still under warranty with it only being 1 year old.
If they say they can’t find a problem again, it’s staying at the dealership until they do find one.
I see.... you are under warranty so Dealer can't get anything done. Obviously they can but not about to make it happen on your schedule.
Give them multiple chance to fix your issue clearly documenting the issues to reproduce.
After sometimes involve MB USA 800 number by opening a case.... they have a very little usefulness. They will contact the local independent dealer.
The survey upon repairs : "pls give me 10 points" BS has some corporate pull but is unlikely to earn any favors by striking 0 score.
The comment anout limp-mode in traffic is when things gets dangerously bad. Right now this is only nagging stage.
You can only hope for the best:
Stay on top of what matters now!
Don't wait for your warranty expiration because then all repairs attemps will be on your dime + "courtesy carwash" because they're so nice to customers.
There is nothing you can do personally to a warranty vehicle otherwise "you caused all the issues".
What's wrong is a common built-in disruption of CAN networks MB Dealer may durably fix under 30mn.
Last edited by CaliBenzDriver; Oct 7, 2025 at 04:06 PM.
2023 E 450 Sedan. 2018 GLC 300. 2013 E 350 Coupe (retired)
Start documenting, look up the lemon laws in your state. Unfortunately, if they can't fix it this would be your best option. Also, consider taking to another dealership who might try harder to fix it. You do not have to live with this!
Last edited by smiles201; Oct 7, 2025 at 01:03 PM.
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