Circuit Description

The 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. Code is set when manifold mounted oxygen sensor signal voltage is .45 volt or more and exhaust pipe mounted oxygen sensor signal voltage is .45 volt or less under the following conditions:

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