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Bulletin #: 2201

Advanced Technical Information

Part ID: 8770

Taycan: Mechanical Noises from the Driver’s Side of Dashboard
Vehicles Affected
Models

Model Year

Model Type

VIN Range

Vehicle-Specific Equipment

Taycan

2020 - 2021

Y1A/ Y1B

N/A

N/A

Revision History
Revision

Release Date

Changes

0

January 27, 2022

Original document

Condition
The customer complains of a noise from the driver’s side of the dashboard. The noise is typically faint and may be
described as a scratching or rattling noise, or a noise that sounds like a servo motor adjusting.
See attached sound file: K109998 Noise.mp4
To open the attachment, download the pdf and click on the paperclip icon to the left of your Adobe Acrobat
window. If the paperclip is not visible, pass your mouse pointer over the lower part of the Acrobat window
and the Acrobat toolbar should appear as seen below. Click on the Acrobat icon on the far right to access
the paperclip, then click on the paperclip to open the attachment.

Technical Background
Hysteresis is the phenomenon in which a physical value lags behind the effect that causes changes to the value.
Common examples of hysteresis are backlash between gears in a gear set or materials not completely returning to
their original form after being stretched.

AfterSales

January 27, 2022
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Bulletin #: 2201

Advanced Technical Information

Part ID: 8770

8

The expansion valve contained in the evaporator in the air conditioning refrigerant circuit has hysteresis values
stored in its internal memory from the supplier. After the thermal management control unit (TME) goes to sleep,
these stored hysteresis values may be erased. The TME does not compensate for the erased hysteresis values.
Therefore, when the valve’s direction of movement is changed in a valve control activation which is less than a given
hysteresis threshold, the worm gear clacks in the way a loaded spring would, and the position sensor on the gear
drive can be indexed. The gear drive compensates for this behavior through cyclical motor control, resulting in the
audible noise heard.

Figure 1: Refrigerant Circuit

Service Information
Please note that the loss of these hysteresis values produces no noticeable impact to the customer on vehicle
operation. There is also no impact to the safety of the vehicle.
There is currently no permanent fix for this condition. Software changes for the TME that correct this condition have
been made in production starting with model year 2022 vehicles. As of January 2022, this software is expected to
be available for earlier model year vehicles in the second half of 2022.
In critical cases, please replace the expansion valve, part no. 9A781668200, per Workshop Manual WM 877019
Removing and installing expansion valve 1.

AfterSales

January 27, 2022
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8

Bulletin #: 2201

Advanced Technical Information

Part ID: 8770

Warranty
As always, be sure to document the repair completely in PQIS.
For this repair, please code the “cause” as follows:
Cause location:
87700
Expansion valve
Cause symptom:
1111
Adjustment fault
Use the following troubleshooting labor operation:
03350050
On board diagnostic
19381756
Coolant drain and fill
19010756
Coolant system bleed
27031900
Voltage converter remove and reinstall
87031750
Refrigerant drain and fill (use ONLY if filling R134a)
87031760
Refrigerant drain and fill (use ONLY if filling with R1234yf)
87031750 and 87031760 cannot be claimed together. Only one of these labor operations is
allowed per repair.
87701950 Expansion valve remove and reinstall

Search Items
Taycan, noise, dashboard, dash, scratching, expansion valve

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.

K10998
©2022 Porsche Cars North America, Inc.

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January 27, 2022
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