Automatic transmission fluid (ATF) is a fluid used in automatic transmission vehicles. It is generally red or green to differentiate it from engine oil and other vehicle fluids. This fluid is optimized to meet special transmission requirements, such as valve operation, gear lubrication and belt friction, brakes, and Torque Converter Clutch (TCC).
The DTC P0218 OBDII code is generic and is set by the PCM (Powertrain Control Module) when the transmission fluid temperature is above the limits set by the manufacturer. Generally, for this code, the fluid temperature must be higher than 290 ℉.