1.Working Principle Built-in negative temperature coefficient NTC thermistor: Low oil temperature → high resistance; high oil temperature → low resistance. TCU identifies oil temperature through resistance changes and adjusts shift strategy, torque lock and cooling control. 2. Standard Technical Parameters Nominal resistance R25: 10kΩ, 20kΩ B-value: 3950K / 4100K Temperature accuracy: ±1℃ ~ ±2℃ Operating temperature range: -40℃ ~ 150℃ (sustained high oil temperature working environment) Oil resistance: Resist automatic transmission fluid, gear oil, no corrosion 3. Structure Design Glass sealed high-temperature NTC chip (stable under long-term high heat) Metal stainless steel / brass sensing housing (good oil heat conduction) Threaded mounting structure or plug-in built-in type for gearbox assembly Oil-resistant, high-temperature FEP wire harness Automotive waterproof plastic connector (IP67 waterproof grade) Sealing rubber gasket to prevent gear oil leakage 4. Core Functions Cold shift optimization When transmission oil is cold (low temperature, high viscosity), TCU delays shifting and reduces torque to avoid rough gear shifts and gear wear. Overheat protection for transmission If oil temperature exceeds safety threshold, TCU triggers limp mode: limit power, lock gear position to prevent gearbox ablation and friction plate burnout. Transmission cooling control Adjust the oil cooler flow / radiator fan speed to cool down overheated ATF oil. Torque converter lock-up control Adjust lock-up timing according to oil temperature to reduce fuel consumption. Dashboard temperature warning Transmit abnormal high temperature signal to instrument panel to remind drivers of gearbox overheating risk. 5. Common Fault Symptoms Rough, delayed gear shifting when vehicle cold Transmission enters limp mode, cannot shift into high gears Gearbox overheating warning light on dashboard Abnormal high fuel consumption Fault code stored in TCU, poor acceleration performance 6. Application Scope Automatic transmission (AT), CVT continuously variable transmission, DCT dual-clutch transmission for passenger cars, pickup trucks, commercial vehicles and engineering machinery.