Diagnostic Aids
WARNING: This page is about a different car, the 2002 Isuzu Rodeo Sport and 2002 Isuzu Rodeo. However, it is still accessible from the selected car via links, so may be relevant.
An intermittent problem can be caused by:
- Check HO2S pigtail wire for breaks, contamination or grounding on exhaust manifold. Check for intermittent ground in signal wire between sensor connector and sensor.
- Misrouted harness, rubbed-through wire insulation or broken wire inside insulation.
- Poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage.
- To diagnose a faulty HO2S heater or heater circuit. After a cool down period, turn ignition on, engine not running. Use scan tool to observe HO2S voltage. HO2S voltage should gradually drop to about 250 mV. If parameter does not display as specified, turn ignition off and disconnect suspect HO2S 4-pin harness connector. Connect test light between ignition feed and heater ground circuit. See WIRING DIAGRAMS article. Turn ignition on. Test light should illuminate. If test light does not illuminate, repair open in ignition feed or ground. If test light illuminates, replace suspect HO2S.
- If no obvious problem with harness is found, use scan tool to monitor HO2S voltage parameter while moving harness connectors and wiring harness. A change in display indicates source of fault.