Adding brake fluid confusion

2005 E2. Trying to add brake fluid and the top of the master cylinder has a notation….clean filler caps before removing. Well that didn’t happen cause I had to remove the top to read it😁. I have no idea what this means!
Also, when looking inside there is a sliding white plate with electric connections. I assume this activates a code when fluid gets low.
Do I just pour the new fluid on top of that plate?


I assume this activates a code when fluid gets low.

It turns on the brake warning light on the dash pod display. This is sometimes is confusing as the same light warns you when the e-brake lever is up/on.

Depending on how much brake fluid you had to add, you might also be concerned as to where the fluid is going.

It is not generally considered a consumable as a brake system is supposed to be closed system.

Grab a flashlight and look at the backside of each brake assembly down near the bottom to see if it is wet. Maybe look at the inside of the rims and extreme cases will have streaks of fluid flung out across the sidewall of the tire. This would indicate a leaky brake cylinder. If so- you should start thinking about a full 4 wheel brake job.

Greatly appreciate the quickbrespinse

Now I know why my emergency light never goes off. Thanks

To check if it is a fluid low condition add fluid.
A quick check would be to unplug the sensor in the reservoir and see if your light goes out. (not the one in the brake line. That is different)