E/W214: ADAS control units glitching in warm weather
Thread Starter
Junior Member
Joined: May 2024
Posts: 20
Likes: 3
volvo
ADAS control units glitching in warm weather
Hi there,
My car, a 2025 E350 displays the following messages on a hot days when the A/C is off and the car is driven for a while. "Active Emergency Stop Assist Inoperative", ""Active Brake Assist Functions Limited See Operator's Manual", "Active Blind Spot Assist and Exit Warning Inoperative", and "Active Brake Assist Functions Limited See Operator's Manual". If the AC is turned on "Auto", this doesn't seem to happen. It also happened to one of my friends with a 2025 GLC 43 AMG and happened in a 2025 E450 Station Wagon loaner car. I am wondering if this is a systemic issue.
See a short video of the issue here:
https://app.box.com/s/vc9bewe8gmk167zu0waziv8857g2o1yp
Does this happen to other people?
Please let me know.
My car, a 2025 E350 displays the following messages on a hot days when the A/C is off and the car is driven for a while. "Active Emergency Stop Assist Inoperative", ""Active Brake Assist Functions Limited See Operator's Manual", "Active Blind Spot Assist and Exit Warning Inoperative", and "Active Brake Assist Functions Limited See Operator's Manual". If the AC is turned on "Auto", this doesn't seem to happen. It also happened to one of my friends with a 2025 GLC 43 AMG and happened in a 2025 E450 Station Wagon loaner car. I am wondering if this is a systemic issue.
See a short video of the issue here:
https://app.box.com/s/vc9bewe8gmk167zu0waziv8857g2o1yp
Does this happen to other people?
Please let me know.
Last edited by mrizzy; Jul 7, 2025 at 03:53 PM.
MBWorld Fanatic!
Joined: Aug 2014
Posts: 1,908
Likes: 665
From: Tennessee
W214 E450
My AC is always on auto when driving and I would never drive with it in any other setting. However, I don't see how one can be related to the other. Yes, some components for those systems may be inside of the vehicle, but most components are outside and not benefiting from an internal AC. Seems odd that this would be the reason, but I'll never know since I don't drive without the AC on and in auto mode.
Super Member
Joined: Dec 2004
Posts: 783
Likes: 22
From: Atlanta
06 E55 Black
I had the active brake assist give me that message the other day but AC was on on Auto
See dirty front sensor, dirty windshield, low battery voltage, temporary software error followed by shop visit if persists
See dirty front sensor, dirty windshield, low battery voltage, temporary software error followed by shop visit if persists
Last edited by regor60; Jul 7, 2025 at 04:38 PM.
MBWorld Fanatic!
Joined: Aug 2014
Posts: 1,908
Likes: 665
From: Tennessee
W214 E450
@L1Wolf Thank you. Do you have ADAS (Advanced Drives Assistance Systems) ? If so, would you mind experimenting ?
MBWorld Fanatic!
Joined: Aug 2014
Posts: 1,908
Likes: 665
From: Tennessee
W214 E450
I have had the message for emergency brake assist being inoperable. Turned out to be a loose connection in the steering column. It has never happened since the dealership fixed it back in December.
Thread Starter
Junior Member
Joined: May 2024
Posts: 20
Likes: 3
volvo
Yes, I have all the driver assist packages. How long do you drive with the AC off? No way I could for more than a few minutes. It's in the upper 90's where I live every day. It's also not good to run with the AC off as it can allow mold to grow in the ducts. The AC dries the air and reduces moisture build up.
I didn’t say keep it off all the time. Maybe just try for 20 minutes or so. I’m trying to see if this is a systemic issue. My car has already been in the shop multiple times for this issue.
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Junior Member
Joined: Jul 2003
Posts: 41
Likes: 4
From: Washington, D.C.
15 cls 550
I had the same problem. Dealer fixed it with updates and securing some connections to the sensors in rear bumper. Problem solved but now a/c only blows through defroster vents when in auto mode. Going in tomorrow.
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Junior Member
Joined: May 2024
Posts: 62
Likes: 19
From: NorCal
S214
Happened to me last night. 2025 E450 All Terrain with 650 miles on it so far. Had driven to the store (up the highway a bit, so I let it drive itself... cruise control and active steering) and everything worked fine. Came out of the store and started the car and it noted errors -- both the emergency brake assist and also the lane keeping assist being inoperative. AC was on auto as always. Cruise control would not work on the drive home.
Got home, read the manual where is says 'turn the car off, then on" (being a computer scientist, I just shudder every time some software engineer tells me to restart/reboot... this means they have no clue what's wrong and are hoping maybe it won't happen again, or at least for a while!) Anyway, I went out and restarted and it worked as expected. Certainly, lost some confidence in the car with this glitch. Will be buying a OBD tool to get some insight into the internal workings and errors.
Got home, read the manual where is says 'turn the car off, then on" (being a computer scientist, I just shudder every time some software engineer tells me to restart/reboot... this means they have no clue what's wrong and are hoping maybe it won't happen again, or at least for a while!) Anyway, I went out and restarted and it worked as expected. Certainly, lost some confidence in the car with this glitch. Will be buying a OBD tool to get some insight into the internal workings and errors.
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