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.
Test H: Step 29: Notes
29) Continuous Memory Code 41 or 91 (With Exhaust Odor or Smoke) Codes 41 or 91 indicate that a HEGO circuit has not switched during closed loop fuel control. In this situation a Code 41 or 91 may not indicate a lean condition. Diagnose all other driveability complaints (see SYMPTOMS in TESTS W/O CODES article) before attempting to service a Continuous Memory Code 41 or 91. Check the following areas:
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.