Circuit Description

The rear oxygen sensor mounted between catalytic converters monitors exhaust gas oxygen content and delivers an input signal to ECM. The ECM uses input signal to determine fuel injection system operation. DTC is set when manifold mounted oxygen sensor (main sensor) signal voltage is .45 volts or more and exhaust pipe mounted oxygen sensor (sub-sensor) signal voltage is .45 volts or less under the following conditions:

• Engine coolant temperature is 176°F (80°C) or more.
• Engine speed is 1500 RPM or more.
• Accelerator pedal is fully depressed for 2 seconds or more.