46 Audi frequency analysis
46 18 85 2051095/1 May 1, 2018.
Model(s)

Year

VIN Range

Vehicle-Specific Equipment

All

2010 - 2019

All

Not Applicable

Condition
This bulletin is informational only and can help technicians to identify noise frequency for specific concerns related
to the brake system, especially brake squeal.

Technical Background
Brake squeal is the most common brake noise concern received from customers. This bulletin will help you to
identify the correct frequency for the concern.
Knowing the exact frequency can help Audi of America to understand the issue and find a feasible solution (for
example: new pad materials, new pad geometry, new backing plate, new spring design, balance weight, and etc.).
Remember that brake squeal is a normal result of multiple factors acting on the brake system.
Brake squeal is not a defect.

Production Solution
Not applicable.

Service
Download the Audi Frequency Analysis App according to the instructions below:
1. Go to Audi B2B App Shop at: https://b2bappshop.audi.de.
2. Sign in with your Global User-ID and Password.
3. Click on “Sign In” (Figure 1).
4. Select the type of device: iOS or Android (Figure 2).

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© 2018 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.

Figure 1. Sign in screen.

Figure 2. Select the type of device.

5. Click on “Install” to start downloading the App (Figure 3).
6. Example of the downloaded App in an iPhone (Figure 4).

Page 2 of 8
© 2018 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.

Figure 3. Installing the APP.

Figure 4. Example of the downloaded app and app
shop.

Page 3 of 8
© 2018 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.

If you receive the following iPhone error message
(Figure 5) “Untrusted Enterprise Developer” after
clicking on the app then follow the Tip below. Skip to
next figure for Android.

Tip: Go to: Phone Settings >> General >>
Profiles & Device Management >> Enterprise
APP>>Audi AG >> Trust Audi AG.

Figure 5. Error message “Untrusted Enterprise
Developer”.

Page 4 of 8
© 2018 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.

If you receive the following Android error message
(Figure 6): “This type of file can harm your device. Do
you want to keep Waveform-release-1.9-sign.apk
anyway?”.
Tip: Select “OK” and proceed with the installation
process.

Figure 6. Error message for Android Phone.

7. After opening the app, see the following example of the main screen (Figure 7).
8. To start frequency analysis, select “Record” (Aufnehmen). There are other functions also available: Play
(Abspielen), Cut (Schneiden), and Export (Exportieren) (Figure 8).

Page 5 of 8
© 2018 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.

Figure 7. Example of the main screen.

Figure 8. To start analysis, select Aufnehmen.

9.

You will be able to record the brake squeal from inside or outside the vehicle, depending on conditions.

10.

Example of a typical brake squeal at 1,6 KHz. The red scale can be moved to identify the main frequency
causing the squeal. Be aware that there are a lot of surrounding noises that can disguise the main
frequency focus (Figure 9).

11.

Example of a typical brake squeal at 3,2 KHz. Also at the top right the date is recorded, exact frequency,
and level of noise in dB (Figure 10).

Page 6 of 8
© 2018 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.

Figure 9. Other sounds can disguise the main
frequency.

Figure 10. Typical brake squeal frequency recording.

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

Page 7 of 8
© 2018 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.

Additional Information
All parts and service references provided in this TSB (2051095) 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.
©2018 Audi of America, Inc. All rights reserved. Information contained in this document is based on the latest
information available at the time of printing and is subject to the copyright and other intellectual property rights of
Audi of America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any
time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted in
any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these
materials be modified or reposted to other sites without the prior expressed written permission of the publisher.

Page 8 of 8
© 2018 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.