This bulletin applies to 2019-2022 Mazda3 and 2018-2021 Mazda6 vehicles.
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
- Engine temperature gauge fluctuates
- The low coolant temperature blue indicator light stays on longer or comes on while driving
- Poor heater performance, especially at idle
Note this does not apply to vehicles with SKYACTIV-G 2.5T.
Due to the production variety of the failsafe thermostat integrated into the coolant control valve, engine coolant may enter into a dry hollow in the failsafe thermostat, resulting in the unintended opening of the thermostat at lower temperatures (104-176 degrees Fahrenheit). To eliminate the concern, the production process of the coolant control valve has been modified.
1. Verify the concern and check the coolant temperature in the freeze frame data. If it is at around 104-176 degrees Fahrenheit, proceed to step two.
2. Replace the coolant control valve. P/N PYFD-15-16ZA for A/T; PYFA-15-16ZB for M/T.
3. Warm up the engine and confirm that the primary malfunction is resolved.
