TSB 01-001-26B — Mazda Service bulletin
01-001-26B is a service bulletin on file with NHTSA for 3 Mazda models, 2018–2025 model years. A TSB is factory repair guidance, not a recall — the repair is not automatically free.
What the bulletin says. 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…
NHTSA's own summary of the document, quoted from the public manufacturer-communications file.
Vehicles and model years 01-001-26B names
| Vehicle | Model years |
|---|---|
| Mazda CX-5 | 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025 |
| Mazda Mazda3 | 2019, 2022 |
| Mazda Mazda6 | 2018, 2019, 2020, 2021 |
Every document filed under 01-001-26B
| Document ID | Filed | Type |
|---|---|---|
| 01-001-26b | March 4, 2026 | Service bulletin |
What 01-001-26B covers
Engine — the component vocabulary NHTSA files this communication under.
Questions buyers ask
What is TSB 01-001-26B?
01-001-26B is a service bulletin filed with NHTSA by Mazda, covering 3 Mazda models across the 2018–2025 model years. NHTSA's summary reads: 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…
Which vehicles does 01-001-26B cover?
NHTSA's file names Mazda CX-5 (2018–2025); Mazda Mazda3 (2019, 2022); Mazda Mazda6 (2018–2021). A bulletin number can be re-issued against more vehicles later, so check the model-year list on this page against your own.
Is TSB 01-001-26B a recall, and is the repair free?
No. 01-001-26B is repair guidance the manufacturer sent its dealers, not a safety defect finding. You pay for the work unless the vehicle is still under warranty. Recall repairs, by contrast, are always free.
How do I get the full text of 01-001-26B?
Take the document ID to a dealer's service desk, or search NHTSA's manufacturer-communications records. This page carries every document ID filed under 01-001-26B, its date, and NHTSA's own summary from the public file.
Every number on this page is a count of records in the federal complaint, recall, and investigation files published by NHTSA's Office of Defects Investigation. This page lists only what NHTSA's manufacturer-communications file records under 01-001-26B. Check any specific vehicle's open recalls by VIN at nhtsa.gov/recalls.