Circuit Description
WARNING: This page is about a different car, the 2002 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.
Heated Air/Fuel (A/F) sensors monitor exhaust gas oxygen content and deliver input signals to ECM. Heated A/F sensors are located on each exhaust manifold. Heated A/F sensor on rear (firewall side) exhaust manifold may also be referred to as bank No. 1 sensor No. 1. Heated A/F sensor on front (radiator side) exhaust manifold may also be referred to as bank No. 2 sensor No. 1. A/F sensors may also be referred to as A/F ratio sensors. ECM uses input signals to determine fuel injection system operation. DTC is set when A/F sensor heater current draw exceeds 8 amps or is .25 amp or less when heater operates. Possible causes are:
- A/F sensor circuit is open or shorted.
- Defective A/F sensor.
- Defective A/F heater relay.
- Defective ECM.