9100 Brake Fluid Level Too Low / Cable Has Open Circuit.
Thread Starter
Senior Member
Joined: Mar 2018
Posts: 493
Likes: 182
2006 W221 S500L M273
9100 Brake Fluid Level Too Low / Cable Has Open Circuit.
When braking for a red light yesterday, some errors popped up on the dash, speedtronic and distronic were disabled and it had the orange triangle with exclamation mark on.
These all went away when i restarted the car.
Now after scanning these DTCs came up:
9100: Brake Fluid Level Too Low / Cable Has Open Circuit. (active)
5970: Check brake system for leaks (stored)
5952: Check brake system for leaks (stored)
5871: Check brake system for leaks (stored)
I checked the brake fluid level and it is still as full as it was weeks ago.
There are no obvious problems with the electrical connection and wiring to the brakefluid level sensor.
Any hints?
These all went away when i restarted the car.
Now after scanning these DTCs came up:
9100: Brake Fluid Level Too Low / Cable Has Open Circuit. (active)
5970: Check brake system for leaks (stored)
5952: Check brake system for leaks (stored)
5871: Check brake system for leaks (stored)
I checked the brake fluid level and it is still as full as it was weeks ago.
There are no obvious problems with the electrical connection and wiring to the brakefluid level sensor.
Any hints?
Last edited by Jaap; Feb 22, 2025 at 09:06 AM.
Thread Starter
Senior Member
Joined: Mar 2018
Posts: 493
Likes: 182
2006 W221 S500L M273
I measured the sensor on the fluid reservoir and it was indeed an open circuit no matter how much i wiggled.
The pins are deeply recessed in their connectorhousing but i'm pretty confident i got the prongs on them correctly.
It's a shame you can't get that sensor separately (or even get it out of the reservoir).
The pins are deeply recessed in their connectorhousing but i'm pretty confident i got the prongs on them correctly.
It's a shame you can't get that sensor separately (or even get it out of the reservoir).
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Joined: Jan 2018
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From: Atlanta GA
2012 E350 Cabriolet now SOLD to my son
When in doubt ...measure twice before replacing anything... lol... cool you found it ..
Now would be a good time to fix the leak, do a full brake inspection and then do a complete brake flush with the best fluid you can buy.
Now would be a good time to fix the leak, do a full brake inspection and then do a complete brake flush with the best fluid you can buy.
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S500
Another BOTUS knocking Merc piece - but it matters - and if the world was still round there'd be a recall over it
Mercedes make all their hard brake lines from the most pathetic junk possible - they are light years worse than that used by any other car manufacturer - I'd say a minimum of ten time less durable than any other brand uses
In the UK every motor vehicle tech and road worthyness test centre would agree - And they will also agree, all German branded manu use utter **** to produce their alloy wheels too
Mercedes make all their hard brake lines from the most pathetic junk possible - they are light years worse than that used by any other car manufacturer - I'd say a minimum of ten time less durable than any other brand uses
In the UK every motor vehicle tech and road worthyness test centre would agree - And they will also agree, all German branded manu use utter **** to produce their alloy wheels too
