Air/Fuel (A/F) Heater Relay (ES300 & RX300)
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2003 Lexus SC 430, 2003 Lexus RX 300, 2003 Lexus LX 470, 2003 Lexus LS 430, and 2003 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.
A/F heater relay relay may also be referred to as A/F HTR. A/F HTR 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 . When A/F HTR is energized by MREL terminal of Engine Control Module (ECM), A/F HTR provides battery voltage to +B terminal at A/F ratio sensor.