Code 44: O2 Sensor Lean 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 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 or cold sensor will cause an open loop condition.

NOTE: Test numbers refer to test numbers on diagnostic chart.

Code 44 will set under following conditions:
- Coolant temperature is greater than 158°F (70°C).
- Engine running for more than 50 seconds.
- Integrator count is not at 128.
- No Code 21A, 21B, 33A, or 33B is set.
- Oxygen sensor voltage is below .278 mV for 99 seconds.
- System is in closed loop.
- TPS is greater than 3 percent.