Brake Sensor problems of the 2007 Volvo S40

Tl- the contact owns a 2007 Volvo S40. The contact stated that the brake sensor illuminated indicating low brake fluid. The vehicle was taken to an authorized dealer. The technician replenished the brake fluid and reset the brake sensor. The contact indicated that shortly after the brake sensor was reset by the dealer, the failure recurred. The vehicle was taken to an independent repair shop who was not able to replicate or diagnose the failure. The vehicle was not repaired. The contact was not included in recall NHTSA campaign number: 08v101000 (brakes). The manufacturer was notified of the failure. The approximate failure mileage was 65,000. Pam.