Code 44 - Lean Exhaust Indication: Notes

The ECM supplies a voltage of about .45 volt between circuits No. 412 and 413 (terminals D7 and D6). The oxygen sensor varies the voltage from one volt (rich exhaust) to .1 volt (lean exhaust). The sensor acts like an open sensor circuit and produces no voltage when exhaust temperature is below 600°F (316°C). An open sensor circuit or cold sensor causes open loop operation. A Code 44 is set when oxygen sensor signal at ECM is below .2 volts for one minute or more, or if time since engine start is one minute or longer.

1. A Code 44 is set when the oxygen sensor signal voltage on circuit No. 412 remains below .2 volt for 50 seconds and the system is operating in "closed loop".