All Other Engines: Notes

Disconnect the PCV valve hose from the PCV valve.

Start engine and run at approximately 2000 RPM. DVOM should indicate less than 0.4 volt within 30 seconds. If not, replace HEGO sensor. Reconnect vacuum hoses and repeat QUICK TEST. If voltage is to specification, HEGO sensor is okay. If engine has sequential PFI, fuel delivery is okay, problem is in an area common to all cylinders, such as a vacuum leak, fuel contamination, EGR system, MAP frequency, etc. Service as necessary. For all other engines, go to step 1) of this test.

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: