1. Disconnect the negative battery cable.
2. Disconnect the sensor connector.
3. Inspect for continuity between terminals of fluid level sensor.
Mazda 6 Service Manual: Shift Gear (Shifting) Speed Limit
For each gear position while in the manual mode, the speed limit is set as follows:
When the selector lever is operated within the range of the speed limit, the gear
is shifted.
Shift up
The gear does not shift up while the vehicle speed is lower than the speed limit.
Shift down
The gear d ...
Mazda 6 Service Manual: Contact Authorized Mazda Dealer and Have Vehicle Inspected
If any of the following warning lights or the indicator light turns on/flashes,
the system may have a malfunction. Contact an Authorized Mazda Dealer to have your
vehicle inspected.
...