Test H: Step 12
12) Checking HEGO Sensor on Engines With MAP Sensors Turn key off and set DVOM on 20-volt scale. Disconnect appropriate HEGO sensor from vehicle harness. Connect DVOM to HEGO SIGNAL lead at sensor and engine ground. Apply 10-14 in Hg to Manifold Absolute Pressure (MAP) sensor and start engine. Run engine at 2000 RPM for 2 minutes. If reading is greater than 0.5 volt, go to step 15). If reading is less than 0.5 volt, replace HEGO sensor, reconnect MAP, and rerun QUICK TEST.
NOTE:
Vacuum or air leaks in non-EEC-IV related areas may cause Code 41 or 91. Check the following areas: leaking vacuum actuator (A/C control motor, etc.) engine seals, EGR system, PCV system and lead contamination of HEGO sensor.
NOTE:
Vacuum or air leaks in non-EEC-IV related areas may cause Code 41 or 91. Check the following areas: leaking vacuum actuator (A/C control motor, etc.) engine seals, EGR system, PCV system and lead contamination of HEGO sensor.
NOTE:
There is a break in the step numbering sequence at this point, skipping from step 12) to step 14). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.