Circuit Description

Heated Air/Fuel (A/F) sensor (bank No. 1 sensor No. 1) monitors exhaust gas oxygen content and delivers input signals to ECM. Heated A/F sensor (bank No. 1 sensor No. 1) is located on exhaust manifold above catalytic converters. See Figure. A/F sensor may also be referred to as A/F ratio sensor. ECM uses input signals to determine fuel injection system operation. DTC is set when A/F sensor (bank No. 1 sensor No. 1) heater current draw exceeds 8 amps or is .25 amp or less when heater operates. Possible causes are:

• A/F sensor (bank No. 1 sensor No. 1) circuit is open or shorted.
• Defective A/F sensor (bank No. 1 sensor No. 1).
• Defective A/F heater relay.
• Defective ECM.