With TBI

Fig. 057 Chart - Code 44 Lean Exhaust Indication:

Fig. 059 - Wiring Diagram for Code 44 Lean Exhaust Indication. VIN 0, VIN 2, VIN E, VIN R, VIN U:

CODE 44

LEAN EXHAUST INDICATION

1.8L "J" AND 2.5L "A & N" SERIES

FUEL INJECTION (TBI)



The ECM supplies a voltage of about .45 volt between Circuits 412 and 413. (If measured with a 10 megohm digital voltmeter, this may read as low as .32 volts.) The O2 sensor varies the voltage within a range of about 1 volt if the exhaust is rich, down through about .10 volt if exhaust is lean.
The sensor is like an open circuit and produces no voltage when it is below about 310°C (600°F) An open sensor circuit or cold sensor causes open loop operation.
Code 44 is set when the O2 sensor signal voltage at the ECM Circuit 412:
a. Remains below .2 volt for 50 seconds idling or more;
b. Time since engine start is 1 minutes or longer
Diagnostic Aids:
1. Grounding the diagnostic terminal with the engine running, enables the "Field Service Mode" and allows the ECM to confirm either open or closed loop operation.
2. A light out or "Open Loop" indicates the fault is present. Disconnecting the O2 sensor will raise the signal voltage above .2 volt. If the ECM and wiring are OK, the ECM should recognize the higher voltage, .35 to .55, and flash open loop when the engine is started.
3. The Code 44 or lean exhaust is most likely caused by one of the following:
a 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.
b. 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.
c. 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 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.
d. If the above are OK, and the instructions at the top of the chart will still set a Code 44, or "SERVICE ENGINE SOON" light is "OFF" more than "ON", or flashing "OPEN LOOP", it is a faulty Oxygen Sensor.