Code 44, O2 Sensor CKT/Lean Exhaust Indicated

ECM supplies a voltage of approximately .43 volt between ECM terminals D6 and D7. If voltage is measured with a 10-megohm DVOM, reading may be as low as .32 volt. The O2 sensor varies voltage within range of .1 volt (lean exhaust) to 1 volt (rich exhaust). When sensor temperature is less than 600°F (316°C), the sensor acts like an open circuit and will not produce voltage. A cold sensor, or open sensor circuit, causes open Loop condition.

1. Code 44 is set when O2 sensor signal voltage is fixed above .280 mV, TPS is more than 3 percent, Codes 21 and 33 are not present, system is in closed loop, coolant temperature is less than 155°F (68°C), and integrator count is not at 128.