DTC 44

Fig. 022 - Wiring Diagram for Code 44 Lean Exhaust Indication. VIN C:

CODE 44, LEAN EXHAUST INDICATION

The ECM supplies a voltage of about .45 volt between terminals "3" and "20". (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 315°C (600°F). An open sensor circuit or cold sensor causes open loop operation.
Trouble Code 44 says that the ECM has seen O2 sensor voltage under the following conditions:
a. Voltage lower than specified
b. Closed loop
c. Above 25% TPS value.
d. For a time longer than 51 seconds and above 2000 RPM

Fig. 021 - Chart - Code 44 Lean Exhaust Indication.:

1. Check to see if the condition is still present. A fixed dwell of under 15° indicates the problem is still present. A fixed dwell under 15° at idle with it varying dwell at 3000 RPM usually indicates an intake leak. Check these areas prior to replacing the O2 sensor.
2. Check to see if the ECM is able to respond to a rich condition caused by choking the engine. If it does, the problem is a lean engine condition,. NOT electrical.
2a. If dwell increases to over 50° with heavy choking, the fault is an air leak since the ECM was able to respond. If air is going to exhaust ports, disconnect the solenoid(s) for the air control valve.
3. This step puts a rich O2 signal (about 1 volt) into Terminal "3" of the ECM. Dwell should increase (lean command).