Code 44, Lean Exhaust Indication
The ECM supplies a voltage of about .45 volt between terminals No. 3 and 20. (If measured with a 10-megaohm digital voltmeter, this may read as low as .32 volts). The O2 sensor varies voltage within a range of about one volt if exhaust is rich, down to about .1 volt if exhaust is lean. The sensor circuit is like an open circuit until the sensor is above 600°F (315°C). An open sensor circuit or a defective sensor will cause open loop operation. Code 44 indicates the ECM has sensed O2 sensor voltage under the following conditions: voltage lower than specified, closed loop, above 25% TPS value, for a time longer than 51 seconds and above 2000 RPM.
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- 1) A fixed dwell under 15 degrees indicates problem is still present. A fixed dwell under 15 degrees at idle and varying dwell at 3000 RPM usually indicates an intake leak. Check this before replacing O2 sensor.
- 2) This test checks if the ECM is able to respond to a rich condition caused by choking the engine. If ECM responds, problem is a lean engine condition, NOT ELECTRICAL.
- 2A) If dwell increases to over 50 degrees with heavy choking, fault is an air leak since the ECM was able to respond. If air is going to the exhaust ports, disconnect the solenoid(s) for the air control valve.
- 3) This step puts a rich O2 signal (about one volt) into terminal No. 3 of the ECM. Dwell should increase (lean command).