No. 171-21

Symptom-based workshop manual
Service
171/21 ENU
4770
4
Symptom - Creaking/Squeaking Noises When Operating the Brake Pedal: Bleeding the
Brake System (SY 171/21)
Revision:
This bulletin replaces bulletin Group 4 171/21, dated February 17, 2022.
Model Year:
As of 2019
Vehicle Type:
Cayenne E-Hybrid (9YA)/Cayenne Turbo S E-Hybrid (9YA)/Cayenne E-Hybrid Coupe
(9YB)/Cayenne Turbo S E-Hybrid Coupe (9YB)
Concerns:
Brake system
Symptom:
The customer complains of a creaking/ squeaking noise at times when the foot brake is operated.
Cause:
Hybrid vehicles have a valve in the hydraulic unit that separates the wheel brakes on the rear axle from the
brake master cylinder during recuperative braking. Technically, the smallest air bubbles can form in the
immediate vicinity of this valve, which can cause the described noise symptoms under certain conditions
(depending on outside temperature, among other things). Otherwise, these smallest air bubbles have no
effect on braking behavior.
Information
This behavior is technically necessary and is state-of-the-art. This does not affect the efficiency of the
brake system.
Remedial
Action:
Bleed the brake system according to the various routines.
Component replacement will not work in this case.
3D Information: You can find a noise recording of a vehicle for which a complaint has been received under the following
link.
4770IN Brake Booster Information
Required tools
Tool:
•
Brake filling and bleeding equipment, e.g. VAS 6860 - Brake filling and bleeding equipment
Bleeding the brake system
Work
Procedure:
To do this, perform the following routines in the specified sequence.
•
Conventional bleeding.
AfterSales
Jan 24, 2023
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4
Service
ENU 171/21
4770
•
•
Symptom-based workshop manual
Commissioning electric brake booster (eBKV)
Porsche Stability Management (PSM) bleeding routine
For instructions, see:
 Workshop Manual '470107 Bleeding the brake system'
Invoicing
Invoicing:
For documentation and warranty invoicing, enter the working position and PCSS encryption specified
below in the warranty claim:
APOS
Labor operation
47010715
Bleeding the brake system
I No.
PCSS encryption:
Location (FES5)
47700
Brake booster
Damage type (SA4)
2017
jars, creaks
References:
 Workshop Manual '470107 Bleeding the brake system'
Important Notice: Technical Bulletins issued by Porsche Cars North America, Inc. are intended only for use by professional automotive technicians who have attended Porsche service training
courses. They are written to inform those technicians of conditions that may occur on some Porsche vehicles, or to provide information that could assist in the proper servicing of a vehicle. Porsche special
tools may be necessary in order to perform certain operations identified in these bulletins. Use of tools and procedures other than those Porsche recommends in these bulletins may be detrimental to the
safe operation of your vehicle, and may endanger the people working on it. Properly trained Porsche technicians have the equipment, tools, safety instructions, and know-how to do the job properly and
safely. Part numbers listed in these bulletins are for reference only. The work procedures updated electronically in the Porsche PIWIS diagnostic and testing device take precedence and, in the event of a
discrepancy, the work procedures in the PIWIS Tester are the ones that must be followed.
© 2023 Porsche Cars North America, Inc.
Jan 24, 2023
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