Mazda Automatic Transmission Speed Sensor
Part Number: FN01-21-550
Replacement automatic transmission speed sensor for selected Mazda vehicles.
This sensor monitors the rotational speed inside the automatic transmission and sends the information to the vehicle’s transmission control system. A faulty sensor can cause incorrect gear changes, transmission warning lights, limp mode, or speed-related fault codes.
Common Symptoms of a Faulty Sensor
🔧 Harsh, delayed, or incorrect gear changes
⚠️ Check Engine or automatic transmission warning light
🚗 Transmission entering limp mode
📉 Incorrect or missing transmission speed readings
💡 Hold or O/D light flashing
🔍 Transmission speed sensor fault codes
Compatible Vehicles
May fit selected automatic transmission models, including:
• Mazda 2
• Mazda 3 / Axela
• Mazda 5 / Premacy
• Mazda 6 / Atenza
• Mazda CX-7
• Mazda CX-9
• Mazda Familia / Protege
• Mazda Protege5
Part Number
Mazda: FN01-21-550
Also written as FN0121550
Important Fitment Information
Mazda vehicles may use multiple transmission sensors that look similar but perform different functions. Please compare the part number and connector with your original sensor before ordering.
Providing your registration or full chassis number is recommended so compatibility can be checked.
What You Receive
1 × Mazda automatic transmission speed sensor
