Code 44 - Lean Exhaust Indication
Code 44 indicates that the ECM has seen O2 sensor voltage (at ECM terminal "D7") lower than .2 volts for 1 minute or more, 2 minutes after engine start. The ECM supplies a voltage of about .45 volt between terms. "D6" and "D7". The O2 sensor varies the voltage from 1 volt (rich indication) to .10 volt (lean indication). An open sensor circuit or a bad sensor causes open loop operation.
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- This test allows the ECM to confirm either open or closed loop operation.
- A light out or "open loop" indicates presence of fault. Disconnecting the O2 sensor will raise the signal voltage above .2 volt. If the ECM and wiring are good, the ECM should recognize the higher voltage, .35 to .55 volt, and flash "open loop" when the engine is started.
- Code 44 or lean exhaust is most likely the result of: Open circuit 413, fuel pressure too low, fuel contaminated, O2 sensor wire grounded, EGR not opening, or MAP sensor giving false low pressure reading. If these 6 systems are found to be operating, O2 sensor is faulty.