Code 45, Oxygen Sensor Circuit Rich Exhaust Indicated

The ECM supplies a voltage of approximately .45 volt between ECM terminals No. 3 and 20 (if measurement is taken with a 10-megohm DVOM, reading may be as low as .32 volt). O2 sensor varies the voltage within a range of about one volt if exhaust is rich and down to about .10 volt if exhaust is lean. When sensor temperature is less than 600°F (316°C), the sensor acts like an open circuit and will not produce voltage. An open sensor circuit will cause an "Open Loop"" condition

1. Code 45 will set when O2 sensor signal voltage on circuit No. 412 remains less than .6 volt for 2 minutes or more, system operating in "Closed Loop", O2 sensor has reached a temperature of 158°F (70°C) and engine is running for 5 minutes or more at part throttle