Mazda CX-3 2018–2025 — technical service bulletin
Bulletin 01-003-25a · NHTSA communication 11026901 · issued Dec 4, 2025
Technical service bulletin
communication type
Engine
component
2018–2025
model years
24
vehicle entries
Official summary
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
Vehicles covered
- 2019 Mazda CX-3
- 2020 Mazda CX-3
- 2021 Mazda CX-3
- 2020 Mazda CX-30
- 2021 Mazda CX-30
- 2022 Mazda CX-30
- 2023 Mazda CX-30
- 2018 Mazda CX-5
- 2019 Mazda CX-5
- 2020 Mazda CX-5
- 2021 Mazda CX-5
- 2022 Mazda CX-5
- 2023 Mazda CX-5
- 2024 Mazda CX-5
- 2025 Mazda CX-5
- 2019 Mazda MAZDA3
- 2020 Mazda MAZDA3
- 2021 Mazda MAZDA3
- 2022 Mazda MAZDA3
- 2023 Mazda MAZDA3
- 2018 Mazda MAZDA6
- 2019 Mazda MAZDA6
- 2020 Mazda MAZDA6
- 2021 Mazda MAZDA6
What a TSB means. Technical service bulletins are repair guidance manufacturers send to dealers — they are not recalls, and repairs are not automatically free (warranty extensions are an exception worth checking). The full document is available via NHTSA’s vehicle lookup.