Code 45: O2 Sensor Rich Fuel Mixture (Heated Sensor Only): Notes

The ECM supplies a voltage of approximately .45 volt between ECM terminals D6 and D7 (if measurement is taken with a 10-megohm DVOM, reading may be as low as .32 volt). The O2 sensor varies voltage within a range of approximately one volt if exhaust is rich and less than .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 or cold sensor will cause an open loop condition.

1. Code 45 will set when sensor voltage signal is greater than .75 volt under following conditions:
   • Coolant temperature is greater than 158°F (70°C).
   • Integrator count is not at 128.
   • No Code 21A, 21B, 33A, or 33B is set.
   • TPS is greater than 3 percent.
   • System is in closed loop.