Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1990 Pontiac LeMans BaseFACTORY OEM SERVICE PROCEDURE
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 around 150.
- 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 a 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 a Code 44. If Code 44 is intermittent, see INTERMITTENTS in TESTS W/O CODES article.
Factory Service Tools
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.