Symptom-based workshop manual

Service
90/21

ENU

4701

4

Brake Symptom – Brake Pedal Travel Perceived as “Too Far”: Observe Specified Procedure (SY 90/21)
Change overview:
Release

Date

Change

0

09/17/2021

•

First publication

1

09/27/2021

•

‘Reduced braking system efficiency’ symptom removed.

2

07/22/2022

•

Update of possible causes

3

01/20/2023

•
•
•
•

Order types added
Update of further measures
Update of required parts
Update of Labor Operations

4

07/18/2023

•

New software version

5

02/09/2024

•
•
•
•
•
•

‘Hardware replacement’ action removed
Order types added
Labor operations added
Adjustment of brake fluid quantity
Adaptation of software versions to 0190 for all model years
‘Perform functional test of the hydraulic unit’ added to
procedure

6

03/27/2025

•

Function test removed

Model Line:

Taycan (Y1A / Y1B / Y1C)

Model Year:

As of 2020 up to 2024

Concerns:

Brake system

Symptom:

The customer complains that the brake pedal travel is subjectively perceived as “too far”.

Possible
Causes:

•

Bedding-in routine not yet completed

The new brake must be ground in on new vehicles or after replacing brake pads. The vehicle will take over this
responsibility automatically by deactivating recuperation for a short time. The bedding-in routine can be up
to 1,000 km/ 620 mls, depending on driving style.
•

‘Brake Refresh’ function

The new ‘Brake Refresh’ function was introduced from model year M (2021). This function is used to
maintain the friction coefficient of the brakes. Recuperation is deactivated briefly during this time.

AfterSales

Mar 27, 2025
Page 1 of 5

4

Service
4701

ENU

•

Symptom-based workshop manual

90/21

‘Stiff Learning Routine’ function

During regenerative braking (recuperation), the electric braking torque of the electric machine has to be
replaced with the hydraulic braking torque of the wheel brakes (‘blending’) at least once during braking,
usually shortly before the vehicle comes to a standstill.
In order to eliminate longitudinal deceleration fluctuations and brake pedal irritations during ‘blending’, the
actual stiffness of the brake system must be known as accurately as possible to the control units involved
(Porsche Stability Management (PSM) and Electric Brake Booster (eBKV)).
If the ‘stiffness learning routine’ is activated automatically too rarely, the following causes may have been
present:
•
•
•

The vehicle has not been charged for a long time.
The temperature of the brake discs was > 100°C (212°F) when the learning process was attempted and
that of the brake callipers was > 55°C (131°F).
The front wheels were regularly turned in too far when leaving the vehicle.

•

Generally, pedal travel is longer when manoeuvring.

In order to improve the metering action of the brakes while parking, a smaller brake master cylinder (HBZ) is
installed in the Taycan compared with the PHEV vehicles, which extends the pedal travel in order to ensure
better metering when parking and manoeuvring. In addition, both brake circuits are opened fully at speeds of
< 12 km/h/ 7 mph for noise, vibration and other comfort reasons, which also results in longer pedal travel.
•

Poor friction coefficient of Porsche Ceramic Composite Brake (PCCB) and Porsche Surface Coated
Brake (PSCB) compared to grey cast iron brakes in wet and/or cold weather conditions.

This effect can adjust when switching from electric to hydraulic braking. This can result in a change in brake
pedal feel during braking with the same pedal pressure.
Action:

1

Check completion of braking routine.
The break-in routine must be completed. If the braking routine has not yet been completed, the “active”
error code “C1399F0 - Operating brake, Grinding-in process active” will still be visible in the Porsche
Stability Management (PSM) control unit.
Further information can be found in the ‘Braking’ section of the Driver’s Manual. ⇒ Betriebsanleitung

2

"Brake Refresh" and "Stiffness learning routine" functions
Ensure that the latest software is on the PSM control unit. To do this, carry out workshop campaign
WPK0 if the vehicle is affected by this and it has not yet been carried out in the past. ⇒ Technical Information 'WPK0 Workshop campaign - Re-program PSM control unit'

3

Generally, pedal travel is longer when manoeuvring.
The state of the art has changed and vehicle operation seems unfamiliar at first. The new functions and
corresponding behavior of the vehicle must be communicated to the customer. The Driver’s Manual for
the vehicle can be used here if necessary. ⇒ Betriebsanleitung

Mar 27, 2025
Page 2 of 5

AfterSales

Service

Symptom-based workshop manual
4

90/21

ENU

4701

4

Poor friction coefficient of Porsche Ceramic Composite Brake (PCCB) and Porsche Surface Coated
Brake (PSCB) compared to grey cast iron brakes in wet and/or cold weather conditions.
The state of the art has changed and vehicle operation seems unfamiliar at first. The differences
between the brake systems and their behavior in appropriate weather conditions must be communicated to the customer. Section: 'Brake'⇒ Betriebsanleitung

Required tools
Tools:

•
•
•
•
•

P90999 - PIWIS Tester 4
Battery charger with a current rating of at least 90 A, e.g., VAS 5908 90-A battery charger. For further
information about the battery chargers to be used, see the corresponding Workshop Manual. ⇒
Workshop Manual '270689 Charge battery and vehicle electrical system'
Charger for high-voltage battery, e.g., VAS 681 003A - Charger for high-voltage battery
VAS 6860 - Brake Filling and Bleeding Equipment
VAS 6122 - Engine plug set

Further actions
Work
Procedure:

If, after working through and taking note of all the points listed, the brake pedal travel is still not adequate for
comparison vehicles, carry out the following further steps:
1

Read out the ‘Stiffness offset wheel brake’ learning value in the PSM control unit under ‘Measured
values’.
Learning value ‘wheel brake rigidity offset’

Action

> 4 mm (0.15748 inch)

Bleed the brake system.
Go to ⇒ 2.

< 4 mm (0.15748 inch)

2

Inform the customer of the causes described
above. Carry out further measures/analyses only
after consultation with the importer’s Technical
Support.

Bleed the brake system. ⇒ Workshop Manual '470107 Bleeding brake system'
Information
The bleeding routine must be carried out as described in Step 1) in the table in the Workshop Manual
"470107 Bleeding the brake system", even if the electric brake booster (eBKV) has not yet been
replaced.

3

Charge high-voltage battery for at least 60 seconds and then remove high-voltage charger (rigidity
learning routine is initiated).
The steering must be in the straight-forward position (steering angle near 0°).
⇒ Workshop Manual '270889 Charging high-voltage battery'

AfterSales

Mar 27, 2025
Page 3 of 5

4

Service
4701

ENU

4

Symptom-based workshop manual

90/21

After bleeding the brake system, read out the ‘Stiffness offset wheel brake’ learning value in the PSM
control unit under ‘Measured values’ again.
Learning value ‘wheel brake rigidity offset’

Action

3 mm (0.11811 inch)

Replace PSM control unit incl. hydraulic unit

⇒ Workshop Manual '453055 Replace hydraulic
unit' (includes automatic programming of the
PSM control unit)

Required parts and materials as needed
Parts Info:

Required parts if the PSM control unit including hydraulic unit needs to be replaced.
Part No.

Designation
– Location

Number

9J1614095SY

⇒ Hydraulic unit

1 piece

or
Only for vehicles with special conversions/installations in production (M-no. S1G)
9J1614095MY
Material:

⇒ Hydraulic unit

1 piece

Required materials (usually already available in the Porsche Center):
Part No.

Designation
– Location

Quantity

00004321086

⇒ Brake fluid, 30-liter/ 7.92 gal container
- Brake system

Quantity as required*

Information
*
Approx. 1.25 liter/ 1.32 qt of brake fluid is required for conventional bleeding.
Approx. 3 liter/ 3.17 qt of brake fluid is required to replace the hydraulic unit.
Approx. 4.5 liter/ 4.75 qt of brake fluid is required for bleeding in conjunction with the "wheel brake rigidity
offset" test.

Mar 27, 2025
Page 4 of 5

AfterSales

Service

Symptom-based workshop manual

90/21

ENU

4701

4

Labor position and PCSS encryption
Information
Invoicing is only possible if the brake system has been bled because no appropriate brake pedal travel has
been set for comparison vehicles even after processing and noting all the points listed.
Labor position:
APOS

Labor operation

I No.

47010750

Bleeding brake system (in conventional way)

47010753

Bleeding brake system (PSM)

47010756

Bleeding brake system (eBKV)

44052006

Removing and mounting 4 wheels

45305500

Replacing hydraulic unit

03350060

On-board diagnosis
PCSS encryption:

Location (FES5)

47010

Subjectively unpleasant

Damage type (SA4)

1615

brake system function

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.

© 2025 Porsche Cars North America, Inc.

AfterSales

Mar 27, 2025
Page 5 of 5