Hyundai Ioniq: Brake System / Troubleshooting

Hyundai Ioniq (AE) 2017-2025 Service Manual / Brake System / Troubleshooting

Troubleshooting

Symptom	Suspect Area	Reference
Lower pedal or spongy pedal	1. Integrated Brake Actuation Unit (Air in)	air·bleed
	2. AHB system (Fluid leaks)	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 distorted)	replace
	3. Piston (Stuck)	replace
	4. Piston (Frozen)	replace
	5. Anchor or Return spring (Inoperative)	replace
	6. Master cylinder (Inoperative)	replace
	7. IBAU (Inoperative)	replace
Brake pull	1. Piston (Sticking)	replace
	2. Pad or lining (Oily)	replace
	3. Piston (Frozen)	replace
	4. Disc (Scored)	replace
	5. Pad or lining (Cracked or distorted)	replace
Hard pedal but brake inefficient	1. Brake system (Fluid leaks)	repair
	2. Brake system (Air in)	air·bleed
	3. Pad or lining (Worn)	replace
	4. Pad or lining (Cracked or distorted)	replace
	5. Rear brake shoe clearance(Out of adjustment)	adjust
	6. Pad or lining (Oily)	replace
	7. Pad or lining (Glazed)	replace
	8. Disc (Scored)	replace
	9. IBAU (Inoperative)	replace
	10. PSU (Inoperative)	replace
Noise from brake	1. Pad or lining (Cracked or distorted)	replace
	2. Installation bolt (Loosen)	adjust
	3. Disc (Scored)	replace
	4. Sliding pin (Worn)	replace
	5. Pad or lining (Dirty)	clean
	6. Pad or lining (Glazed)	replace
	7. Brake pad shim (Damage)	replace
Brake fades	1. Pad or lining (Worn)	replace
Brake fades	2. Master cylinder (Inoperative)	replace
Brake vibration, pulsation	1. Pedal free play	adjust
	2. Master cylinder (Inoperative)	replace
	3. Caliper (Damage)	replace
	4. Master cylinder cap seal	replace
	5. Damaged brake lines	replace
Heavey pedal (Halt)	1. Brake pedal sticking (lack of grease)	repair
Heavey pedal (Halt)	2. IBAU (Inoperative)	replace
Motor sounds and excessive time to braking when consecutive 2 or 3 times pushing brake pedal (In the case of that accumulator pressure increase rate is under 5bar/sec when checking sensor figures of AHB with GDS)	1. AHB system (air in)	air·bleed
	2. PSU (Inoperative)	replace
Excessive noise when pushing brake pedal	1. IBAU/PSU system (air in)	air·bleed

It is not the malfunction of brake when motor sound is noticed with followings.

–	Repeated pushing brake pedal

–	Pushing and releasing brake pedal with power off.

–	Opening a door of driver side

It is not the malfunction of brake while a brake pedal seems inoperative with followings.

–	Noise when pushing brake pedal fast

–	Noise when pushing brake pedal consecutively

Special service tools

Special Service Tools Tool (Number and Name) Illustration Use 09581-2T100Piston expanderSpreading the front and rear disc brake piston...

Brake bleeding procedures

Integrated Electronic Brake (IEB) System Air Bleeding Procedures • Do not reuse the drained fluid.• Always use genuine DOT3 or DOT4 brake Fluid...

Other information:

Hyundai Ioniq (AE) 2017-2025 Service Manual: Troubleshooting

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Hyundai Ioniq (AE) 2017-2025 Service Manual: Fuel Pump Control Module (FPCM). Description and operation

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