Code 45 - Rich Exhaust Indication: Notes

The ECM supplies a voltage of about .45 volts between terminals "D6" and "D7". If measured with a 10-megohms digital voltmeter, this may read as low as .32 volts. The O2 sensor varies the voltage within a range of about one volt if the exhaust is rich, down through about .10 volts if exhaust is lean. The sensor is like an open circuit and produces no voltage when it is below about 600°F (360°C). An open sensor circuit or cold sensor causes "open loop" operation.

1. A Code 45 is set when the oxygen sensor signal voltage or circuit No. 412, remains above .7 volt for 50 seconds and in "closed loop". Engine time after start is one minute or more. Throttle angle greater than 2% (about .2 volts above idle voltage) but less than 25%.