Subaru Legacy BN/BS (2015-2019) Service Manual: General diagnostic table inspection

1. Insufficient braking

(1) Fluid leakage from the hydraulic mechanism

Repair or replace. (cup, piston seal, piston boot, master cylinder piston kit, pipe or hose)

(2) Entry of air into the hydraulic mechanism

Bleed air.

(3) Wear, deteriorated surface material, water or fluid on pad

Replace and clean.

(4) Improper operation of master cylinder assembly, disc caliper, vacuum booster assembly or check valve

Repair or replace.

2. Unstable or uneven braking

(1) Fluid on pad or rotor

Correct the cause of fluid leakage, and replace.

(2) Rotor defective

Repair or replace the rotor.

(3) Improper pad contact, deteriorated surface, deteriorated or worn pad material

Replace.

(4) Deformed back plate

Repair or replace.

(5) Overinflation of tires

Adjust the air pressure.

(6) Defective wheel alignment

Adjust alignment.

(7) Loose back plate or support installation bolt

Tighten to the specified torque.

(8) Defective hub unit COMPL

Replace.

(9) Defective hydraulic system

Replace the cylinder, brake pipe or hose.

(10) Unstable performance of the parking brake

Check, adjust or replace the rear brake.

3. Excessive pedal stroke

(1) Entry of air into the hydraulic mechanism

Bleed air.

(2) Excessive play in the master cylinder push rod

Adjust.

(3) Fluid leakage from the hydraulic mechanism

Repair or replace. (cup, piston seal, piston boot, master cylinder piston kit, pipe or hose)

(4) Improper pad contact or worn pad

Repair or replace.

4. Brake dragging or improper brake return

(1) Insufficient pedal play

Adjust play.

(2) Improper master cylinder return

Clean or replace the cylinder.

(3) Clogged hydraulic system

Replace.

(4) Improper return of parking brake

Repair or replace.

(5) Improper disc caliper operation

Repair or replace.

(6) Faulty wheel bearing

Replace.

5. Brake noise (1) (creaking sound)

(1) Hardened or deteriorated brake pad

Replace the pad.

(2) Worn brake pad

Replace the pad.

(3) Loose back plate or support installation bolt

Tighten to the specified torque.

(4) Loose hub unit COMPL

Tighten to the specified torque.

(5) Dirty rotor

Clean the rotor, or clean and replace brake assembly.

6. Brake noise (2) (hissing sound)

(1) Worn brake pad

Replace the pad.

(2) Improperly installed pad

Correct or replace the pad.

(3) Loose or bent rotor

Retighten or replace.

7. Brake noise (3) (click sound)

Excessively worn pad or support

Replace the pad or the support.