DTC 44

Code 44 Chart:

Code 44 Wiring Diagram:

CIRCUIT DESCRIPTION:


The ECM supplies a voltage of about 0.45 volt between terminals "GE14" and "GE15." (If measured with a 10 megohm digital volt meter, this may read as low as 0.32 volt.) The 02 sensor varies the voltage within a range of about 1 volt if the exhaust is rich, down through about 0.10 volt if exhaust is lean.

The sensor is like an open circuit and produces no voltage when it is below 316~C (600~F). An open sensor circuit or cold sensor causes "Open Loop" operation.


TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. Code 44 is set when the 02 sensor signal voltage on CKT 412:

^ Remains below 0.3 volt for 90 seconds or more.
^ The system is operating in "Closed Loop".
^ No Code 33 or 34.
^ "Closed Loop" integrator active.
^ TPS above 5%.

DIAGNOSTIC AIDS:

The Code 44 or lean exhaust is most likely caused by one of the following:

^ 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. Related Tests, Information and Procedures
^ MAP Sensor - An output that causes the ECM to sense a lower than normal manifold pressure (high vacuum) can cause the system to go lean. Disconnecting the MAP sensor will allow the ECM to substitute a fixed (default) value for the MAP sensor. If the rich condition is gone when the sensor is disconnected, substitute a known good sensor and recheck.

^ 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.

^ Sensor Harness - Sensor pigtail may be mis-positioned and contacting the exhaust manifold.

^ Engine Misfire - A cylinder misfire will result in unburned oxygen in the exhaust, which could cause Code 44. Chart C-4M Ignition System Check

^ Cracked O2 sensor - A cracked O2 sensor or poor ground could cause a Code 44. Testing and Inspection

^ Plugged Fuel Filter - A plugged fuel filter can cause a lean condition, and cause a Code 44 to set.