P0126 · Manufacturer communications

MAZDA · 2026-09-25

Subject: Notification of Dealer Re-Work (DRW59) – 2026MY CX-30 and 2026MY Mazda3 - Check Engine Light On With DTC P0126:00 Dear Mazda Dealer Colleagues, Mazda Motor Corporation has decided to conduct a Dealer Re-Work on certain 2026MY CX-30 and Mazda3 vehicles. Concern Outline: On certain subject vehicles, the check engine light may illuminate with DTC P0126:00 (Thermostat stuck open) stored due to improper PCM control logic. Repair Outline: Reprogram the PCM with the Mazda Modular Diagnostic System (M-MDS), using Mazda Diagnostic and Repair Software (MDARS) by following TSB 01-006/26 repair instructions. ACTION ITEM - STOP DELIVERY: All affected vehicles in inventory can be sold but not delivered until repaired. There are approximately 17,942 new vehicles in dealer stock and/or in…

MAZDA · 2026-03-25

Subject: Notification of Dealer Re-Work (DRW59) – 2026MY CX-30 and 2026MY Mazda3 - Check Engine Light On With DTC P0126:00 Dear Mazda Dealer Colleagues, Mazda Motor Corporation has decided to conduct a Dealer Re-Work on certain 2026MY CX-30 and Mazda3 vehicles. Concern Outline: On certain subject vehicles, the check engine light may illuminate with DTC P0126:00 (Thermostat stuck open) stored due to improper PCM control logic. Repair Outline: Reprogram the PCM with the Mazda Modular Diagnostic System (M-MDS), using Mazda Diagnostic and Repair Software (MDARS) by following TSB 01-006/26 repair instructions. ACTION ITEM - STOP DELIVERY: All affected vehicles in inventory can be sold but not delivered until repaired. There are approximately 17,942 new vehicles in dealer stock and/or in…

MAZDA · 2026-03-25

Subject: Notification of Dealer Re-Work (DRW59) – 2026MY CX-30 and 2026MY Mazda3 - Check Engine Light On With DTC P0126:00 Dear Mazda Dealer Colleagues, Mazda Motor Corporation has decided to conduct a Dealer Re-Work on certain 2026MY CX-30 and Mazda3 vehicles. Concern Outline: On certain subject vehicles, the check engine light may illuminate with DTC P0126:00 (Thermostat stuck open) stored due to improper PCM control logic. Repair Outline: Reprogram the PCM with the Mazda Modular Diagnostic System (M-MDS), using Mazda Diagnostic and Repair Software (MDARS) by following TSB 01-006/26 repair instructions. ACTION ITEM - STOP DELIVERY: All affected vehicles in inventory can be sold but not delivered until repaired. There are approximately 17,942 new vehicles in dealer stock and/or in…

MAZDA · 2026-03-25

Subject: Notification of Dealer Re-Work (DRW59) – 2026MY CX-30 and 2026MY Mazda3 - Check Engine Light On With DTC P0126:00 Dear Mazda Dealer Colleagues, Mazda Motor Corporation has decided to conduct a Dealer Re-Work on certain 2026MY CX-30 and Mazda3 vehicles. Concern Outline: On certain subject vehicles, the check engine light may illuminate with DTC P0126:00 (Thermostat stuck open) stored due to improper PCM control logic. Repair Outline: Reprogram the PCM with the Mazda Modular Diagnostic System (M-MDS), using Mazda Diagnostic and Repair Software (MDARS) by following TSB 01-006/26 repair instructions. ACTION ITEM - STOP DELIVERY: All affected vehicles in inventory can be sold but not delivered until repaired. There are approximately 17,942 new vehicles in dealer stock and/or in…

MAZDA · 2026-03-11

Some customers may experience the check engine light on with DTC P0126:00 (Thermostat stuck open) stored. This is due to improper PCM logic control. To eliminate the concern, the PCM control software has been modified. REPAIR PROCEDURE 1. Verify the customer concern. 2. Reprogram the ECU with the Mazda Modular Diagnostic System (M-MDS), using Mazda Diagnostic and Repair Software (MDARS). Refer to MDARS ECU Reprogramming Procedure. NOTE: Be sure to submit Diagnostic Information (ODR) data as it is a required item and will be checked during warranty claim submission. Instructions can be found under M-MDS -> MDARS (Uploading Diagnostic Information (ODR) Data). 3. Clear any other DTCs. 4. Verify the repair by starting the engine (READY ON) and confirming there is no CHECK ENGINE light ON or…

MAZDA · 2026-03-05

Subject: TSB 01-001/26 Warranty and Parts Kit Update INCLUDES: Warranty Extension Program - Special Service Program (SSP) D8 Check Engine Light ON with DTC P0126:00, 2018-2025 CX-5, 2019-2023 Mazda3, 2019-2022 CX-3, 2018-2021 Mazda6, 2020-2023 CX-30 Dear Mazda Dealer Colleagues, Mazda Motor Corporation has made a change regarding related parts to TSB 01-001/26 which also impacts Warranty Extension Special Service Program (SSPD8). Parts Ordering and Warranty Claims: Effective March 5, 2026 only the related parts kit PYY2-15-SAY can be ordered and claimed for any repair. The two separate parts PYFB-15-169 and PE13-15-296 can no longer be claimed with repaired dates of March 5, 2026 and later. There is no change to the main part, the Plug PYY3-15-SA1. We have updated the TSB 01-001/26 and…

MAZDA · 2026-03-05

Subject: TSB 01-001/26 Warranty and Parts Kit Update INCLUDES: Warranty Extension Program - Special Service Program (SSP) D8 Check Engine Light ON with DTC P0126:00, 2018-2025 CX-5, 2019-2023 Mazda3, 2019-2022 CX-3, 2018-2021 Mazda6, 2020-2023 CX-30 Dear Mazda Dealer Colleagues, Mazda Motor Corporation has made a change regarding related parts to TSB 01-001/26 which also impacts Warranty Extension Special Service Program (SSPD8). Parts Ordering and Warranty Claims: Effective March 5, 2026 only the related parts kit PYY2-15-SAY can be ordered and claimed for any repair. The two separate parts PYFB-15-169 and PE13-15-296 can no longer be claimed with repaired dates of March 5, 2026 and later. There is no change to the main part, the Plug PYY3-15-SA1. We have updated the TSB 01-001/26 and…

MAZDA · 2026-03-04

Some customers may experience a check engine light ON with DTC P0126:00 (Thermostat stuck open) and one or more of the following symptoms: Engine takes longer to warm up. Engine temperature gauge fluctuates. Low coolant temperature indicator (blue) light stays on longer or turns on while driving. Poor heater performance, especially at idle. Vehicles with SKYACTIV-G 2.5T are not applicable to this service information. DTC P0126:00 is not required to be present to perform this repair. If the vehicle has not previously had the repair specified in this TSB and is exhibiting any of the listed symptoms, proceed with the repair procedure outlined in this bulletin. If DTC P2B61:00 (Coolant Control Valve Circuit Range/Performance) is present along with DTC P0126:00, this TSB does not apply.…

MAZDA · 2026-02-06

SSPD8 - Check Engine Light ON with DTC P0126:00 - WARRANTY EXTENSION For certain 2018-2025MY CX-5, 2019-2023MY Mazda3, 2019-2022MY CX-3, 2018-2021MY Mazda6, 2020-2023MY CX-30 that are equipped with the suspected coolant control valve, the warranty coverage for specific repair of the fail-safe thermostat is extended to: 15 years (180 months) or 150,000 miles (240,000 km) whichever comes first, from the original warranty start date. CONDITION OF CONCERN: On certain subject vehicles, the check engine light is illuminated with DTC P0126:00 (Thermostat stuck open) stored in memory and one or more of the following symptoms may occur: - Engine takes longer to warm up. - Engine temperature gauge fluctuates. - Low coolant temperature indicator (blue) light stays on longer or turns on while…

MAZDA · 2026-01-31

Some customers may experience a check engine light ON with DTC P0126:00 (Thermostat stuck open) and one or more of the following symptoms: Engine takes longer to warm up. • Engine temperature gauge fluctuates. • Low coolant temperature indicator (blue) light stays on longer or turns on while driving. • Poor heater performance, especially at idle. • This concern may be caused if the coolant control valve fail-safe thermostat opens at a temperature lower than the normal temperature due to a deformation of the thermostat diaphragm. To eliminate the concern, the water flow control valve specification has been modified.

MAZDA · 2026-01-30

SSPD8 - Check Engine Light ON with DTC P0126:00 - WARRANTY EXTENSION For certain 2018-2025MY CX-5, 2019-2023MY Mazda3, 2019-2022MY CX-3, 2018-2021MY Mazda6, 2020-2023MY CX-30 that are equipped with the suspected coolant control valve, the warranty coverage for specific repair of the fail-safe thermostat is extended to: 15 years (180 months) or 150,000 miles (240,000 km) whichever comes first, from the original warranty start date. CONDITION OF CONCERN: On certain subject vehicles, the check engine light is illuminated with DTC P0126:00 (Thermostat stuck open) stored in memory and one or more of the following symptoms may occur: - Engine takes longer to warm up. - Engine temperature gauge fluctuates. - Low coolant temperature indicator (blue) light stays on longer or turns on while…

MAZDA · 2026-01-30

SSPD8 - Check Engine Light ON with DTC P0126:00 - WARRANTY EXTENSION For certain 2018-2025MY CX-5, 2019-2023MY Mazda3, 2019-2022MY CX-3, 2018-2021MY Mazda6, 2020-2023MY CX-30 that are equipped with the suspected coolant control valve, the warranty coverage for specific repair of the fail-safe thermostat is extended to: 15 years (180 months) or 150,000 miles (240,000 km) whichever comes first, from the original warranty start date. CONDITION OF CONCERN: On certain subject vehicles, the check engine light is illuminated with DTC P0126:00 (Thermostat stuck open) stored in memory and one or more of the following symptoms may occur: - Engine takes longer to warm up. - Engine temperature gauge fluctuates. - Low coolant temperature indicator (blue) light stays on longer or turns on while…

MAZDA · 2026-01-08

Some customers may experience a check engine light ON with DTC P0126:00 (Thermostat stuck open) and one or more of the following symptoms: Engine takes longer to warm up. • Engine temperature gauge fluctuates. • Low coolant temperature indicator (blue) light stays on longer or turns on while driving. • Poor heater performance, especially at idle. • This concern may be caused if the coolant control valve fail-safe thermostat opens at a temperature lower than the normal temperature due to a deformation of the thermostat diaphragm. To eliminate the concern, the water flow control valve specification has been modified.

MAZDA · 2025-12-24

Some customers may experience a check engine light ON with DTC P0126:00 (Thermostat stuck open) and one or more of the following symptoms: Engine takes longer to warm up. • Engine temperature gauge fluctuates. • Low coolant temperature indicator (blue) light stays on longer or turns on while driving. • Poor heater performance, especially at idle. • This concern may be caused if the coolant control valve fail-safe thermostat opens at a temperature lower than the normal temperature due to a deformation of the thermostat diaphragm. To eliminate the concern, the water flow control valve specification has been modified.

MAZDA · 2025-12-23

SSPD8 - Check Engine Light ON with DTC P0126:00 - WARRANTY EXTENSION For certain 2018-2025MY CX-5, 2019-2023MY Mazda3, 2019-2022MY CX-3, 2018-2021MY Mazda6, 2020-2023MY CX-30 that are equipped with the suspected coolant control valve, the warranty coverage for specific repair of the fail-safe thermostat is extended to: 15 years (180 months) or 150,000 miles (240,000 km) whichever comes first, from the original warranty start date. CONDITION OF CONCERN: On certain subject vehicles, the check engine light is illuminated with DTC P0126:00 (Thermostat stuck open) stored in memory and one or more of the following symptoms may occur: - Engine takes longer to warm up. - Engine temperature gauge fluctuates. - Low coolant temperature indicator (blue) light stays on longer or turns on while…

MAZDA · 2025-12-20

Some vehicles equipped with a countermeasure Coolant Control Valve (plug in place of the thermostat inside the CCV) may experience a DTC P0126:00.

MAZDA · 2025-12-11

SSPD8 - Check Engine Light ON with DTC P0126:00 - WARRANTY EXTENSION For certain 2018-2025MY CX-5, 2019-2023MY Mazda3, 2019-2022MY CX-3, 2018-2021MY Mazda6, 2020-2023MY CX-30 that are equipped with the suspected coolant control valve, the warranty coverage for specific repair of the fail-safe thermostat is extended to: 15 years (180 months) or 150,000 miles (240,000 km) whichever comes first, from the original warranty start date. CONDITION OF CONCERN: On certain subject vehicles, the check engine light is illuminated with DTC P0126:00 (Thermostat stuck open) stored in memory and one or more of the following symptoms may occur: - Engine takes longer to warm up. - Engine temperature gauge fluctuates. - Low coolant temperature indicator (blue) light stays on longer or turns on while…

MAZDA · 2025-12-05

SSPD8 - Check Engine Light ON with DTC P0126:00 - WARRANTY EXTENSION For certain 2018-2025MY CX-5, 2019-2023MY Mazda3, 2019-2022MY CX-3, 2018-2021MY Mazda6, 2020-2023MY CX-30 that are equipped with the suspected coolant control valve, the warranty coverage for specific repair of the fail-safe thermostat is extended to: 15 years (180 months) or 150,000 miles (240,000 km) whichever comes first, from the original warranty start date. CONDITION OF CONCERN: On certain subject vehicles, the check engine light is illuminated with DTC P0126:00 (Thermostat stuck open) stored in memory and one or more of the following symptoms may occur: - Engine takes longer to warm up. - Engine temperature gauge fluctuates. - Low coolant temperature indicator (blue) light stays on longer or turns on while…

MAZDA · 2025-12-05

SSPD8 - Check Engine Light ON with DTC P0126:00 - WARRANTY EXTENSION For certain 2018-2025MY CX-5, 2019-2023MY Mazda3, 2019-2022MY CX-3, 2018-2021MY Mazda6, 2020-2023MY CX-30 that are equipped with the suspected coolant control valve, the warranty coverage for specific repair of the fail-safe thermostat is extended to: 15 years (180 months) or 150,000 miles (240,000 km) whichever comes first, from the original warranty start date. CONDITION OF CONCERN: On certain subject vehicles, the check engine light is illuminated with DTC P0126:00 (Thermostat stuck open) stored in memory and one or more of the following symptoms may occur: - Engine takes longer to warm up. - Engine temperature gauge fluctuates. - Low coolant temperature indicator (blue) light stays on longer or turns on while…

MAZDA · 2025-12-04

Some customers may experience a check engine light ON with DTC P0126:00 (Thermostat stuck open) and one or more of the following symptoms: Engine takes longer to warm up. Engine temperature gauge fluctuates. Low coolant temperature indicator (blue) light stays on longer or turns on while driving. Poor heater performance, especially at idle. This concern may be caused if the coolant control valve fail-safe thermostat opens at a temperature lower than the normal temperature due to a deformation of the thermostat diaphragm. To eliminate the concern, the water flow control valve specification has been modified.

MAZDA · 2025-03-13

Some customers may experience a check engine light ON with DTC P0126:00 (Thermostat stuck open) and one or more of the following symptoms: Engine takes longer to warm up. Engine temperature gauge fluctuates. Low coolant temperature indicator (blue) light stays on longer or turns on while driving. Poor heater performance, especially at idle. NOTE: Vehicles with SKYACTIV-G 2.5T are not applicable to this service information. If DTC P2B61:00 (Coolant control valve circuit range/performance) accompanies DTC P0126:00, this TSB is not applicable. Diagnose DTCs according to the instructions on MGSS online.

MAZDA · 2025-03-11

SSPD8 - SPECIAL SERVICE PROGRAM WARRANTY EXTENSION - MULTI-MODEL - CHECK ENGINE LIGHT ON WITH DTC P0126:00.Mazda Motor Corporation has decided to conduct a Special Service Program (SSP) to extend the warranty coverage for a specific repair of the fail-safe thermostat in the coolant control valve on certain CX-5, Mazda3, CX-3, Mazda6 and CX-30 vehicles that are equipped with the suspected coolant control valve. The warranty coverage for a specific repair of fail-safe thermostat has been extended to 15 years (180 months) /150,000 miles (240,000 km) whichever comes first, from the original warranty start date. Concern Outline:On certain subject vehicles, the check engine light is illuminated with DTC P0126:00 (Thermostat stuck open) stored in memory and one or more of the following symptoms…

MAZDA · 2025-03-11

SSPD8 - SPECIAL SERVICE PROGRAM WARRANTY EXTENSION - MULTI-MODEL - CHECK ENGINE LIGHT ON WITH DTC P0126:00.Mazda Motor Corporation has decided to conduct a Special Service Program (SSP) to extend the warranty coverage for a specific repair of the fail-safe thermostat in the coolant control valve on certain CX-5, Mazda3, CX-3, Mazda6 and CX-30 vehicles that are equipped with the suspected coolant control valve. The warranty coverage for a specific repair of fail-safe thermostat has been extended to 15 years (180 months) /150,000 miles (240,000 km) whichever comes first, from the original warranty start date. Concern Outline:On certain subject vehicles, the check engine light is illuminated with DTC P0126:00 (Thermostat stuck open) stored in memory and one or more of the following symptoms…

MAZDA · 2024-12-24

Mazda Motor Corporation has decided to conduct a Special Service Program (SSP) to extend the warranty coverage for a specific repair of the fail-safe thermostat installed inside of the suspected coolant control valve on certain 2018-2025 CX-5, 2019-2023 Mazda3, 2019-2022 CX-3, 2018-2021 Mazda6 and 2020-2023 CX-30 vehicles. The warranty coverage for an applicable repair has been extended to 15 years (180 months) /150,000 miles (240,000 km) whichever comes first, from the original warranty start date. If you are a recipient of this notice, your vehicle is included in this warranty extension program. What is the problem? On certain subject vehicles, the check engine light is illuminated with diagnostic trouble code (DTC) P0126, due to the fail-safe thermostat being stuck open. Additionally,…

MAZDA · 2024-11-09

On certain subject vehicles, the check engine light is illuminated with diagnostic trouble code (DTC) P0126, due to the fail-safe thermostat being stuck open. Additionally, you may notice one or more of the following symptoms: -Engine takes longer to warm up. -Engine temperature gauge fluctuates. -Low coolant temperature indicator (blue) light stays on longer or turns on while driving. -Poor heater performance, especially at idle. This warranty extension program applies only to the replacement of fail-safe thermostat of the vehicle exhibiting the concerns mentioned above. If the check engine light illumination is determined to be unrelated to the fail-safe thermostat being stuck open, the inspection and repair are not covered under this program.

MAZDA · 2024-11-05

Some customers may experience a check engine light ON with DTC P0126:00 (Thermostat stuck open) and one or more of the following symptoms: Engine takes longer to warm up. Engine temperature gauge fluctuates. Low coolant temperature indicator (blue) light stays on longer or turns on while driving. Poor heater performance, especially at idle.

MAZDA · 2024-10-31

Mazda Motor Corporation has decided to conduct a Special Service Program (SSP) to extend the warranty coverage for a specific repair of the fail-safe thermostat in the coolant control valve on certain CX-5, Mazda3, CX-3, Mazda6 and CX-30 vehicles that are equipped with the suspected coolant control valve. The warranty coverage for a specific repair of fail-safe thermostat has been extended to 15 years (180 months) /150,000 miles (240,000 km) whichever comes first, from the original warranty start date. Concern Outline: On certain subject vehicles, the check engine light is illuminated with DTC P0126:00 (Thermostat stuck open) stored in memory and one or more of the following symptoms may occur: Engine takes longer to warm up, Engine temperature gauge fluctuates, Low coolant temperature…

MAZDA · 2024-10-31

Mazda Motor Corporation has decided to conduct a Special Service Program (SSP) to extend the warranty coverage for a specific repair of the fail-safe thermostat in the coolant control valve on certain CX-5, Mazda3, CX-3, Mazda6 and CX-30 vehicles that are equipped with the suspected coolant control valve. The warranty coverage for a specific repair of fail-safe thermostat has been extended to 15 years (180 months) /150,000 miles (240,000 km) whichever comes first, from the original warranty start date. Concern Outline: On certain subject vehicles, the check engine light is illuminated with DTC P0126:00 (Thermostat stuck open) stored in memory and one or more of the following symptoms may occur: Engine takes longer to warm up, Engine temperature gauge fluctuates, Low coolant temperature…

MAZDA · 2024-08-29

Some customers may experience a check engine light ON with DTC P0126:00 (Thermostat stuck open) and one or more of the following symptoms: Engine takes longer to warm up. Engine temperature gauge fluctuates. Low coolant temperature indicator (blue) light stays on longer or turns on while driving. Poor heater performance, especially at idle.

MAZDA · 2024-06-28

Some customers may experience a check engine light ON with DTC P0126:00 (Thermostat stuck open) and one or more of the following symptoms: Engine takes longer to warm up. Engine temperature gauge fluctuates. Low coolant temperature indicator (blue) light stays on longer or turns on while driving. Poor heater performance, especially at idle. NOTE: Vehicles with SKYACTIV-G 2.5T are not applicable to this service information. If DTC P2B61:00 (Coolant control valve circuit range/performance) accompanies DTC P0126:00, this TSB is not applicable. Diagnose DTCs according to the instructions on MGSS online.