Mazda CX-3 2018–2025 — technical service bulletin
Bulletin 01-003-25b · NHTSA communication 11026902 · issued Dec 24, 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 specificat
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.