E044
Code E044 - Oxygen Sensor Circuit (Lean Exhaust Indication):
Wiring Diagram for Code E044 - Oxygen Sensor Circuit (Lean Exhaust Indication):
CODE E044 - OXYGEN SENSOR CIRCUIT (LEAN EXHAUST INDICATION)
Circuit Description:
The ECM supplies a voltage of about 450mv between terminals "D7 and D6". (If measured with a 10 mega-ohm digital voltmeter, this may read as low as 320 mv.) The O2 sensor voltage varies within a range of about 1 volt if the exhaust is rich, down through about 100mv if exhaust is lean.
The sensor generates no voltage when it is below about 360°C (600°F) An open sensor circuit or cold sensor results in open loop operation.
Code E044 is set when:
a. Codes E033 or E034 not present
b. O2 voltage remains below 248mv
c. Closed loop generator not forced to 128
d. Fuel system in closed loop
e. All above conditions present for more than 60 seconds
Test Description: The following numbered steps correspond with the step numbers on the diagnostic chart.
1. Running the engine at 1000 RPM keeps the O2 sensor hot so an accurate display voltage is maintained.
2. Opening the O2 sensor wire should result in a voltage display of between 350 and 550mv. If the display is still fixed below 350mv, the fault is a short to ground in CKT 412 or the ECM is faulty.
Diagnostic Aids:
The Code 44 or lean exhaust is most likely caused by one of the following:
a. Circuit 413 - If circuit 413 is open the voltage at terminal D-7 will be over one volt.
b. Fuel Pressure - System will be lean if pressure is too low. It may be necessary to monitor fuel pressure while driving the car at various road speeds and/or loads to confirm.
c. Fuel contamination - Water, even in small amounts, near the in-tank fuel pump inlet can be delivered to the injector. The water causes a lean exhaust and can set a Code 44.
d. Sensor harness - Sensor pigtail may be mispositioned and contacting the exhaust manifold.
e. MAF sensor - An output that causes the ECM to sense a lower than normal manifold air flow will cause the system to go lean.