ZN Connection offline

Technical Service Bulletin
45 MIL on - DTC P258BO00 or PO055600

Transaction No.: 2072305/3
Release date: Feb 4, 2026

Condition
Model(s) Year(s) VIN Range Vehicle Specific Equipment
Q3 2021 — 2025 All Not applicable

REVISION HISTORY

Revision | Date Purpose
3 - Revised Condition (Added model table, updated information)
2 09/10/2024 | Revised header (Add Model Year)

Revised Service (Updated Information)

1 12/13/2023 | Initial publication

Customer states:

* The MILis ON.

and/or

* The braking assist is too low. Additional brake pedal force is necessary.
and/or

* The brake pedal is too stiff (hard).

and/or

* — The following message is shown in the instrument cluster “Start-stop fault”.
Workshop findings:

* The customer statement can be reproduced.

* | The vacuum pump fuse has blown.

The following DTCs (Static) are logged in the engine control unit -J623- (address word 0001):

* P258B00 Vacuum Pump Control Range.
or

* P055600 Pressure sensor for brake booster, implausible signal.

Additionally, the following DTCs (intermittent/static) may be stored in the engine control unit -J623- (diagnostic

address: 0001):
* U012100: Lost Communication with Anti-Lock Brake System (ABS) Control Module.
* U041500: ABS conirol module implausible signal.

Additional DTCs may be stored in different control units (communication errors) with the ABS control unit.

If there are additional DTCs that indicate other complaints on the vehicle, these DTCs must be processed in
advance according to GFF. Please note that the costs for working through the DTCs cannot be billed to this

[0]

Documentation required

Technical Background

The analyses have shown that the vacuum pump fuse was blown due to the connector of the ABS control unit being
improperly disconnected. The improper separation of the ABS connector and the subsequent running of the engine /
driving operations meant that the vacuum pump exceeded certain internal parameters. As a result, the vacuum
pump fuse blows and the vacuum pump itself can become irreparably damaged / can fail.

The ABS control unit connector can only be unplugged if this is absolutely necessary for diagnostic
purposes in the event of a complaint, or when replacing the ABS control unit.

Proceed as follows in the event of a complaint:
* Take pictures of the ABS control unit/ABS control unit connector and upload to DOC-IT.

* — Check if the connector has been unplugged from the ABS control unit, or if there are any signs of tampering
(e.g., scratches on the connector).

* — Ifthe connector has been unplugged from the ABS control unit or if tampering has been determined, the repair
cannot be billed under warranty.

* Replace triggered / blown vacuum pump fuses according to ELSA>>Repair Manual>>Electrical
System>>Electrical Equipment>>97 Wiring>>Relay Panels, Fuse Panels and E-Box>>Component Location
Overview.

* Check if the vacuum pump works and runs properly as per ELSA>>Repair Manual>>Chassis>>Brake
System>>47 Hydraulic Components>>Vacuum System>>Overview Vacuum Pump.

Figure 1: ABS hydraulic unit / ABS control unit connector.

* If the connector has been unplugged from the ABS control unit or if tampering has been determined,
the repair cannot be billed under warranty.

* Ifthe connector has not been unplugged from the ABS control unit and no tampering has been
determined, this TSB does not apply!

Production Solution

Not applicable.

Service
Not applicable.

Warranty

This TSB is informational only and not applicable to any Audi Warranty.

Additional Information

All part and service references provided in this TSB (2072305) are subject to change and/or removal. Always check
with your Parts Department and/or ETKA for the latest information and parts bulletins. Please check the Repair
Manual for fasteners, bolts, nuts, and screws that require replacement during the repair.

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