Diagnostic Aids
Using scan tester, observe the block learn value at different engine RPM. If the conditions for Code 44 exist, block learn value will be 150 or higher.
- O2 sensor wire pigtail may be mispositioned and contacting exhaust manifold.
- Check for ground in wire between connector and sensor.
- Even a small amount of water contamination near the in-tank fuel pump inlet can be delivered to the injector, causing a lean exhaust and setting Code 44.
- Low fuel pressure can cause a lean exhaust. It may be necessary to monitor fuel pressure while driving car at various road speeds and engine loads.
- Exhaust leaks ahead of O2 sensor can dilute exhaust gases, causing a false lean signal and Code 44. If Code 44 is intermittent, see INTERMITTENTS in TESTS W/O CODES article in this section.