DTC 44

Code 44 Chart:

Code 44 Wiring Diagram:

CIRCUIT DESCRIPTION:

The Electronic Control Module (ECM) supplies a voltage of about 0.45 volt between terminals "D6" and "D7". (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 0.1 volt if exhaust is lean. The sensor is like an open circuit and produces no voltage when it is below about 316~C (600~F). An open sensor circuit or cold sensor causes open loop operation.

NOTE: Because of all the possible color code combinations used on electrical wiring diagrams, always refer to ECM CONNECTOR IDENTIFICATION under ELECTRICAL AND ELECTRONIC WIRING DIAGRAMS for correct color code identification of circuit.

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 6O 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. If the conditions for Code 44 exists the block learn values will be around 150.

^ 02 Sensor Wire may be mis-positioned and contacting the exhaust manifold.

^ Check for intermittent ground in wire between connector and sensor.

^ A Mass Air Flow (MAF) sensor output that causes the ECM to sense a lower than normal air flow will cause the system to go lean. Disconnect the MAF sensor and if the lean condition is gone, replace the MAF sensor or use MAF tester J-36101, or equivalent.

^ Perform injector balance test CHART C-2A

^ 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. See CHART A-7.

^ 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.

^ Air System (manual trans only) Be sure air is not being directed to the exhaust ports while in "Closed Loop". If the block learn value goes down while squeezing air hose to exhaust ports, refer to CHART C-6.

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