Kia Optima Hybrid Owner's Manual Quiz
Brake System

Troubleshooting

In this manual: Brake System
General Information — 4Engine Mechanical System — 50Engine Electrical System — 20Emission Control System — 30Engine Control System/Fuel System — 84Automatic Transmission — 98Drive Shaft and Axle — 15Suspension System — 36Steering — 12Restraints — 50Brake System — 38Body (Interior and Exterior) — 54Body Electrical System — 233Heating, Ventilation, and Air Conditioning — 57
~2min read

Troubleshooting

Symptom Suspect area Reference
Low or Spongy Pedal 1. Integrated brake actuation (air in inlet) Air · Bleed
2. AHB system (fluid leak) Replace
3. Piston seals in IBAU (worn or damaged) Replace
Brake drag 1. Brake pedal free play (minimum) adjust
2. Pad or lining (cracked or deformed) Replace
3. Piston (stuck) Replace
4. Piston (seized) Replace
5. Anchor or return spring (not working) Replace
6. Master cylinder (not working) Replace
7. IBAU (not working) Replace
Brake linkage 1. Piston (sticking) Replace
2. Gasket or lining (greasy) Replace
3. Piston (seized) Replace
4. Disc (scored) Replace
5. Pad or lining (cracked or deformed) Replace
Hard Pedal, but Brakes Are Ineffective 1. Brake system (fluid leak) Repair
2. Brake system (air) Air · Bleed
3. Pad or lining (worn) Replace
4. Pad or lining (cracked or deformed) Replace
5. Rear brake shoe clearance (not adjusted) adjust
6. Gasket or lining (greasy) Replace
7. Shim or Pad (Glazed) Replace
8. Disc (Rated) Replace
9. IBAU (Malfunction) Replace
10. Power Supply (Malfunction) Replace
Brake noise 1. Pad or Lining (Cracks or Deformation) Replace
2. Mounting Bolt (Loose) adjust
3. Disc (Rated) Replace
4. Guide Pin (Worn) Replace
5. Shim or Pad (Dirty) Clean
6. Shim or Pad (Glazed) Replace
7. Brake Pad Shim (Damaged) Replace
Brake fading 1. Pad or Lining (Worn) Replace
2. Master Cylinder (Malfunction) Replace
Brake Vibration, Pulsation 1. Brake Pedal Free Play adjust
2. Master Cylinder (Malfunction) Replace
3. Caliper (Damaged) Replace
4. Master Cylinder Cap Seal Replace
5. Brake Lines Damaged. Replace
Hard Pedal
(Stopping)		 1. Brake Pedal Sticking (Lack of Lubrication) Repair
2. IBAU (Malfunction) Replace
Engine Noise and Excessive Braking Time When Pressing the Brake Pedal 2 or 3 Times in Succession
(If the pressure build-up rate in the hydraulic accumulator is less than 5 bar/sec when checking the AHB sensor readings with GDS)		 1. AHB System (Air Intrusion) Air · Bleed
2. Power Supply (Malfunction) Replace
Excessive Noise When Depressing the Brake Pedal 1. IBAU/PSU System (Air Intrusion) Air · Bleed

This is not a brake malfunction if the following engine sound is heard.
  • Repeated Brake Pedal Depression
  • Depressing and releasing the brake pedal with the power off.
  • Opening the Driver's Door
This is not a brake malfunction if the brake pedal feels inoperative with the following.
  • Noise When Depressing the Brake Pedal Suddenly
  • Noise When Depressing the Brake Pedal in Succession

Test yourself

A quick Kia Optima Hybrid Owner's Manual quiz: every answer comes with an explanation and a link to the manual page.