Air/Fuel (A/F) Heater Relay (ES300 & RX300)
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2002 Lexus SC 430, 2002 Lexus RX 300, 2002 Lexus LX 470, 2002 Lexus LS 430, and 2002 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.
A/F HTR relay may also be referred to as A/F heater relay. A/F HTR relay is located in fuse/relay box near battery. Constant battery voltage is supplied from battery, through A/F HTR (25-amp) fuse to one side of A/F HTR relay. When A/F HTR relay is energized by MREL terminal of Engine Control Module (ECM), A/F HTR relay provides battery voltage to +B terminal at A/F ratio sensor.