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Front Seat Ventilation Does Not Function: Observe Specified Procedure (66/25)
Change Overview
Revision

Date

Change

0

09/03/2025

•

First publication

1

02/03/2026

•

Update of order types, and
MY

Model Line:

Taycan (Y1A / Y1B / Y1C)

Model Year:

As of 2020

Equipment:

Front seat ventilation (M-No. 4D3)
Front seat ventilation / massage seats (M-No. 4D5)

Concerns:

Front backrest surface seat fan
Front seat surface seat fan

Cause:

The customer complains that the seat ventilation of the front left or right seat surface or backrest surface
do not function.
Possible customer complaints:
•
•
•

Seat ventilation cannot be switched on, the pilot lights go off again after one second
Seat ventilation can be switched on via the seat ventilation button (pilot lights remain on), but a fan does
not switch on
Burning smell under the front seat

The following fault memory entries can be stored in the fault memory of the front-end electronics control unit
(BCM1):
Information
The fault memory entries are listed using the "Front left seat ventilation" as an example. Identical entries are
also possible for the right side.
For a general overview of possible fault memory entries, see: ⇒ Technical Information 'Potential fault
memory entries'
•
•
•
•

B14C931 - Front left seat backrest fan, no communication (010383)
B14C907 - Front left seat backrest fan, mechanical fault (010384)
B14C94B - Front left seat backrest fan, temperature too high (010385)
B14C929 - Front left seat backrest fan, implausible signal (010388)

AfterSales

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Action:

Technical Information

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B14C956 - Front left seat backrest fan, part number implausible (010389)
B14CB31 - Front left seat cushion fan, no communication (010399)
B14CB07 - Front left seat cushion fan, mechanical fault (010400)
B14CB4B - Front left seat cushion fan, temperature too high (010401)
B14CB29 - Front left seat cushion fan, implausible signal (010404)
B14CB56 - Front left seat cushion fan, part number implausible (010405)

Check and analyse customer complaint and perform appropriate actions depending on the fault type.

Installation
Location:

1
2

Installation location for backrest surface seat fan for and front seat surface seat fan
– Front backrest surface seat fan
– Front seat surface seat fan

Required tools
Information
Required tools for the release or replacement of the affected seat fan, which are required for performing the
required action, must be determined independently in accordance with the valid Workshop Manual in the
PCSS.

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AfterSales

Service

Technical Information
Tools:

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P90999 - PIWIS Tester 4
Battery charger with a current rating of at least 90 A and a current and voltage-controlled charge map
for lithium starter batteries, e.g. VAS 5908 battery charger 90 A. For further information about the
battery chargers to be used, see the corresponding Workshop Manual. ⇒ Workshop Manual '270689
Charge vehicle electrical system battery'

Checking and evaluating fault type
Work Procedure: 1

Connect and switch on the battery charger.

⇒ Workshop Manual '270689 Charging the vehicle electrical system battery'

2

Connect P90999 - PIWIS Tester 4, establish operational readiness (switching on ignition) and start the
diagnostic application.

3

Read out fault memory of the front-end electronics control unit (BCM1), evaluate fault memory entries
and fault pattern and perform the corresponding action.
Information
The fault memory entries are listed using the "Front left seat ventilation" as an example. Depending
on the customer complaint, it involves one or both seat fans of the respective affected seat ventilation
(backrest surface seat fan and / or seat surface seat fan).
Identical entries are also possible for the right side.
Assessment
One or more of the following fault memory entries are stored
in the fault memory:
•
•
•
•
•
•

B14C956 - Front left seat backrest fan, part number
implausible (010389)
B14C931 - Front left seat backrest fan, no communication (010383)
B14C929 - Front left seat backrest fan, implausible
signal (010388)
B14CB56 - Front left seat cushion fan, part number
implausible (010405)
B14CB31 - Front left seat cushion fan, no communication (010399)
B14CB29 - Front left seat cushion fan, implausible
signal (010404)

AfterSales

Action
Perform recalibration of front seat
ventilation.
⇒ Technical Information '270689
Perform recalibration of front seat
ventilation'

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The customer also complains about a burning smell under
the affected front seat.
The following fault memory entries are stored in the fault
memory:
•
•

B14C931 - Front left seat backrest fan, no communication (010383)
B14CB31 - Front left seat cushion fan, no communication (010399)

Replacing affected backrest surface
seat fan or front seat surface seat fan
⇒ Technical Information '270689
Replacing affected backrest surface
seat fan or front seat surface seat fan'

Optionally also one or more of the following fault memory
entries may also be stored:
•
•
•
•

B14C907 - Front left seat backrest fan, mechanical fault
(010384)
B14C94B - Front left seat backrest fan, temperature too
high (010385)
B14CB4B - Front left seat cushion fan, temperature too
high (010401)
B14CB07 - Front left seat cushion fan, mechanical fault
(010400)

Only the following fault memory entries are stored in the fault Check fuse of affected seat ventilation
memory:
and perform further troubleshooting if
necessary.
•
B14C931 - Front left seat backrest fan, no communi⇒ Technical Information '270689
cation (010383)
Checking fuse and performing further
•
B14CB31 - Front left seat cushion fan, no communitroubleshooting if necessary'
cation (010399)

Perform recalibration of front seat ventilation
Work Procedure: 1

Recalibrate seat ventilation.
Information
When recalibrating, all seat fans of the seat ventilation are automatically retaught.
1.1

Select 'Front-end electronics (BCM1)' control unit.

1.2

Select the 'Maintenance / repairs' menu.

1.3

Perform function 'Calibration of seat ventilation' according to menu guidance.

Information
If the function of the affected seat fan is restored by the recalibration, the action is ended at this point
(continue with Step 5).
If this is not the case: Continue with Step 2.

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Expose affected seat fan.
For procedure, see:
⇒ Workshop Manual '741619A2 Removing and installing backrest surface suction fan'
or
⇒ Workshop Manual '740919A4 Removing and installing front seat surface suction fan'

3

Check wiring of the affected seat fan for damage.
Assessment
( )

Wiring of affected seat fan is OK.

7

Action
Replace affected seat fan.
For procedure, see:
⇒ Workshop Manual '741619A2 Removing and
installing backrest surface suction fan'
or
⇒ Workshop Manual '740919A4 Removing and
installing front seat surface suction fan'
Then continue with Step ⇒ 5.

✗)
(✗

Wiring of affected seat fan is not OK.

Repair wiring and check seat ventilation again.
Then continue with Step ⇒ 4.

4

Complete affected seat fan.
⇒ Workshop Manual '741619A2 Removing and installing backrest surface suction fan'

5

Read out and erase all fault memories.

6

Exit the diagnostic application. End operational readiness (switch off ignition). Disconnect P90999 PIWIS Tester 4 from the vehicle.

7

Switch off and disconnect the battery charger.
⇒ Workshop Manual '270689 Charge vehicle electrical system battery'

End of action.

Replace affected seat fans in backrest surface or front seat surface
1

Replace affected seat fan.
For procedure, see:
⇒ Workshop Manual '741619A2 Removing and installing backrest surface suction fan'
or
⇒ Workshop Manual '740919A4 Removing and installing front seat surface suction fan'

2