SA-035-20

Service Alert
Mazda North American Operations
Irvine, CA 92618-2922
Subject:
CHECK ENGINE LIGHT ON WITH DTC P0126:00 AND ENGINE
RUNNING COOLER THAN NORMAL / POOR HEATER
PERFORMANCE / LOW ENGINE COOLANT TEMPERATURE (BLUE)
LIGHT ON
Service Alert No.: SA-035/20
Last Issued: 02/28/2020
APPLICABLE MODEL(S)/VINS
2018-2020 Mazda6 (non-turbo)
2018-2020 CX-5 (non-turbo)
DESCRIPTION
Some customers may experience the CHECK ENGINE LIGHT ON with DTC P0126:00 (Thermostat stuck
open) and one or more of the following symptoms:




The engine takes longer to warm up.
The engine temperature gauge fluctuates.
The low coolant temperature indicator (blue) light stays on longer or comes on while driving.
Poor heater performance, especially at idle.
REPAIR PROCEDURE
1. Verify customer concern.
2. Remove the engine coolant control valve (1) and inspect the mechanical thermostat (2) to see if it is
open.
NOTE: The rotor (3) is what normally controls coolant flow.
Is the thermostat open?
 Yes:
1. Take a clear photo of the open thermostat. (The photograph is important as the thermostat may
return to the closed position during shipment back to Mazda)
2. Replace the coolant control valve.
3. Contact Hotline for additional instructions and photo collection.
 No:
1. Replace the coolant control valve.
2. Contact Hotline for additional instructions.
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.
02/28/2020 3:50 PM tlawrenc
Service Alert No.: SA-035/20
Last Issued: 02/28/2020
3. Verify repair.
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.
02/28/2020 3:50 PM tlawrenc