Hi,

the one nearby the brake power assist is the only pressure sensor. Unfortunately it tends to fail, I had this one broken on mine as well. Changing the sensor is worth a try. A good reason by the way why the wires had been cut.

Or, the pressure level is indeed too low due to an empty (broken) break pressure reservoir. But in that case the warning should come not immediately after you swtich on the ignition but after a few seconds or after braking.

The two other sensors are the break fluid and the hydraulic fluid level sensors.

Regards

Bastian

Das Buch zum Audi V8