Note. Heated oxygen sensor No. 1 refers to sensor closest to engine block. Heated oxygen sensor No. 2 refers to sensor farthest from engine block.
Circuit Description
Heated oxygen sensor monitors exhaust gas oxygen content and delivers an input signal to ECM. ECM uses input signal to determine fuel injection system operation. Heated oxygen sensor includes a heater. DTC is set when ECM detects a response time of one second or more from heated oxygen sensor to change from rich to lean, or lean to rich when engine is warm and idling. Possible causes are
- Defective heated oxygen sensor No. 1.
- Fuel trim malfunction.
Diagnostic Aids
Using scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.