Code 45 - O2 Sensor (Rich Fuel Mixture): Notes

The ECM supplies a voltage of approximately .45 volt between terminals No. B2 and B3. Oxygen sensor varies voltage from one volt (rich exhaust) to .1 volt (lean exhaust). The sensor acts like an open circuit and produces no voltage when exhaust temperature is less than 680°F (360°C). An open sensor circuit or cold sensor causes open loop operation.

1. A Code 44 is set when oxygen sensor signal voltage on circuit No. B3 remains greater than .1 volt, TPS is greater than 10 percent, Codes 21A, 21B or 33A and 33B are not set, engine has been running for at least 2 minutes, system is operating in closed loop, oxygen sensor voltage is less than .35 and greater than .55 volt, engine is at normal operating temperature, integrator mode is not at 128 counts and all conditions are present for 50 seconds.