Diagnostic Aids
Using a scan tester, observe block learn value at different RPM. The scan tester displays the block cells, so the block learn values can be checked in each of the cells, to determine when Code 44 may have set. If conditions for Code 44 exists, the block learn values will be around 150.
Check for mispositioned O2 sensor pigtail or pigtail contacting exhaust manifold. Check for grounded wire between connector and sensor. Check for fuel contamination, causing a lean exhaust, setting Code 44. Check fuel pressure and for exhaust leaks. Exhaust leaks can cause outside air to be pulled into the exhaust and past the sensor.
The wrong fuel injectors installed in vehicle will also cause a lean condition. If code is intermittent, see TESTS W/O CODES article in this section.