GROUP
CHA

MODEL
2014-2019MY
All Listed Models

NUMBER
098

DATE
August 2019

TECHNICAL SERVICE BULLETIN
IBAU SYSTEM REPAIR GUIDE FOR NOISE
AND AIR BLEEDING

SUBJECT:

This bulletin provides the repair guide for the Integrated Brake Actuation Unit (iBAU) system on
some 2014-2019MY Kia EV/Hybrid/Plug-In Hybrid vehicles listed (see table), which may exhibit
a “Honking” (hissing) noise due to air remaining in the brake fluid system. Perform the air
bleeding procedure outlined in this bulletin for the “Honking (Hissing) noise” concern when
operating the brake pedal. Note: It is not recommended to replace the iBAU, Pressure Source
Unit (PSU) or other related Active Hydraulic Boost (AHB) brake system components for this
noise concern.
iBAU Repair Application Table

iBAU
PSU

Model Vehicle

Model Year

Niro (HEV/PHEV)

2017-2019MY

Optima (HEV/PHEV)

2014-2019MY

Soul (EV)

2015-2019MY

Audio Media Files: Click for “Honk” sample noise.
Video Media File: Click for “IBAU Air Bleeding” procedure.

File Under:
Circulate To:

X General Manager


X Service Advisors


X Technicians


X Service Manager


X Parts Manager


X Body Shop Manager 
X Fleet Repair


Page 2 of 3

IBAU SYSTEM REPAIR GUIDE FOR NOISE AND AIR BLEEDING

SUBJECT:

Comparison between General and iBAU brake systems:

Intergrated Brake Actuation Unit (iBAU):
When a driver presses the brake pedal, the IBAU delivers brake fluid charged in the PSU to the
calipers by opening a valve. When pressing the brake pedal, high pressure brake fluid passes
through the internal IBAU valve. Then, the valve operating sound “click” will be heard.
Pressure Source Unit (PSU):
The PSU continuously charges and stores brake fluid at high pressure (160~180 Bar) by
operating the PSU motor. When a driver presses the brake pedal, the brake fluid is then
delivered to the calipers through the iBAU valve. After pressing the brake pedal, the normal
PSU motor operating sound “grrr” will be heard while it recharges the lowered pressure.
Air Bleeding Procedure:

 NOTICE
The iBAU consists of 3 brake fluid lines in total (low/high pressure and pedal
simulator lines), therefore, air bleeding should be made sequentially following the
procedure below.
Procedure

Step

Repair

iBAU ECU

1

Low Pressure and Simulator Fluid Lines

OFF

2

High Pressure Brake Fluid Line

ON

3

Fluid Circulation Mode with KDS

ON

AHB Brake System Bleeding

1.

Refer to the “Brake System → Brake
Bleeding Procedure” chapter in the
applicable Shop Manual on KGIS.




Air Bleeding Tool Installation
Procedure
AHB Brake System Bleeding
(Steps 1, 2 and 3)
Air Bleeding Tool Removal
Procedure

TSB: CHA098 Multiple Models July 2019

Page 3 of 3

IBAU SYSTEM REPAIR GUIDE FOR NOISE AND AIR BLEEDING

SUBJECT:

AFFECTED VEHICLE RANGE:
Model

Production Date Range

Niro (HEV)

2017MY through 2019MY

Niro (PHEV)

2018MY through 2019MY

Optima (HEV)

2014MY through 2019MY

Optima (PHEV)

2017MY through 2019MY

Soul (EV)

2015MY through 2019MY

REQUIRED TOOL:
Tool Name

Figure

Comments

Located in Kia
SST Cabinet Drawer #7

SST 09580 3D100

WARRANTY INFORMATION:
N Code: Q55 C Code: ZZ3
Model

Claim
Type

Niro
(DE)
EV, PHEV
Optima
(JF)
EV, PHEV
Soul
(PS)
EV

Causal
P/N

Qty.

58732
2T500

58732
B2000

Labor
Op Code

Op
Time

Replacement
P/N

Qty.

58700A1H

1.5
M/H

N/A

0

iBAU System
AHB Brake System
Bleeding

58732
Q4000

W

Repair
Description

0

iBAU System
AHB Brake System
Bleeding
iBAU System
AHB Brake System
Bleeding

TSB: CHA098 Multiple Models August 2019