With Speed Density Update

Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION:
The ECM supplies a voltage of about 0.45 volt between terminals "E14" and "E15." (If measured with a 10 megohm digital voltmeter, this may read as low as 0.32 volt.) The O2 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 about 315°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 O2 sensor signal voltage on CKT 412:
- Remains below 0.2 volt for 60 seconds or more
- And the system is operating in "Closed Loop."

DIAGNOSTIC AIDS:
Using the "Scan," observe the block learn values at different rpm and air flow conditions. The "Scan" also displays the block cells, so the block learn values can be checked in each of the cells to determine when the Code 44 may have been set. If the conditions for Code 44 exist, the block learn values will be around 150.

Sensor Wire. Sensor pigtail may be mispositioned and contacting the exhaust manifold.

Check for intermittent ground in wire between connector and sensor.

Lean Injector/s. Perform injector balance test, see Chart C-2A. Chart C-2A Injector Balance Test

Fuel Contamination. Water, even in small amounts near the in-tank fuel pump inlet can be delivered to the injectors. The water causes a lean exhaust and can set a Code 44.

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. Refer to Fuel System Diagnosis, Chart A-7. Chart A-7 Fuel System Diagnosis

Exhaust Leaks. If there is an exhaust leak, the engine can cause outside air to be pulled into the exhaust and past the sensor. Vacuum or crankcase leaks can cause a lean condition.

If the above are OK, it is a faulty oxygen sensor.