Technical
Service Bulletin

Mazda North American Operations
Irvine, CA 92618-2922

Subject:
UNUSUAL ENGINE NOISE AFTER A COLD ENGINE START

Bulletin No.: 01-011/20

Last Issued: 08/21/2020

BULLETIN NOTES
This bulletin supersedes the previously issued bulletin(s) listed below: The changes are noted in Red.

Previous TSBs: Date(s) Issued:
01-018/16

10/26/2016

01-006/13

2/13/2013

APPLICABLE MODEL(S)/VINS

2012-2013 Mazda3 (SKYACTIV) 2014-2017 Mazda6 2016-2017 Mazda2
2014-2016Mazda3

2013-2016 CX-5

DESCRIPTION
Some customers may complain about an unusual noise coming from the engine compartment for about 20
seconds after a cold engine start. This noise is a normal engine operation for improved exhaust gas
emissions. The noise does not indicate a malfunction.

ACCELERATED WARM-UP SYSTEM (AWS)
All SKYACTIV-G engines adopt AWS to reduce exhaust gas emissions immediately after a cold engine
start. AWS increases the engine idling speed and retards the ignition timing for about 20 seconds after the
cold engine start to quickly warm up the catalytic converter. The customer may identify the engine sound
during the AWS operation as a unusual noise.

Page 1 of 2
CONSUMER NOTICE: The information and instructions in this bulletin are intended for use by skilled technicians. Mazda technicians utilize the proper tools/
equipment and take training to correctly and safely maintain Mazda vehicles. These instructions should not be performed by “do-it-yourselfers.” Customers
should not assume this bulletin applies to their vehicle or that their vehicle will develop the described concern. To determine if the information applies,
customers should contact their nearest authorized Mazda dealership. Mazda North American Operations reserves the right to alter the specifications and
contents of this bulletin without obligation or advance notice. All rights reserved. No part of this bulletin may be reproduced in any form or by any means,
electronic or mechanical---including photocopying and recording and the use of any kind of information storage and retrieval system ---without permission in
writing.

© 2020 Mazda North American Operations, U.S.A.
08/23/2020 8:06 PM tlawrenc

Bulletin No.: 01-011/20

Last Issued: 08/21/2020

AWS OPERATION

a. Engine coolant temperature of less than 113F (145C) at engine start.
b. At idle (accelerator pedal off) with transmission in P, N, or D.
AWS CONTROL

a. Ignition timing is retarded about 20 degrees.
b. Engine speed is increased.
AWS burns fuel inside the exhaust manifold (A) to quickly warm up the catalytic convertor. The customer
may identify the burning sound as an unusual noise.

AWS CANCELATION
AWS is canceled when the vehicle is driven.
AWS IDENTIFICATION

a. Customer states the noise is about 20 seconds after a cold engine start.
b. There is no leakage from the exhaust system.

Page 2 of 2
CONSUMER NOTICE: The information and instructions in this bulletin are intended for use by skilled technicians. Mazda technicians utilize the proper tools/
equipment and take training to correctly and safely maintain Mazda vehicles. These instructions should not be performed by “do-it-yourselfers.” Customers
should not assume this bulletin applies to their vehicle or that their vehicle will develop the described concern. To determine if the information applies,
customers should contact their nearest authorized Mazda dealership. Mazda North American Operations reserves the right to alter the specifications and
contents of this bulletin without obligation or advance notice. All rights reserved. No part of this bulletin may be reproduced in any form or by any means,
electronic or mechanical---including photocopying and recording and the use of any kind of information storage and retrieval system ---without permission in
writing.

© 2020 Mazda North American Operations, U.S.A.
08/23/2020 8:06 PM tlawrenc