For 1990-2009 cars

Causes | Correction
--- | ---
Leaking brake pipe or connection | Locate and repair the brake pipe or the connection.
Leaking caliper piston seal | Replace caliper piston seal.
Leaking master cylinder (internally) | Repair or replace the master cylinder.
Restricted passage in the vacuum booster | Replace the vacuum booster.
Damaged vacuum booster | Replace the vacuum booster.
Restricted brake fluid passage | Locate and repair the brake fluid passage restriction.
Improper rear brake adjustment | Adjust the rear brake linings.