Where is a Chevy Impala 2004 brake fluid sensor located?

The 2004 Chevy Impala's brake fluid level sensor is located within the brake master cylinder reservoir. It's not a separate, easily visible sensor; it's integrated into the reservoir itself. You'll find the master cylinder under the hood, typically near the firewall, and the sensor is inside the reservoir. You won't be able to see it or easily access it without removing the reservoir.