Diagnostic Aids

A restricted fuel filter may supply adequate amount of fuel at idle, but not during heavy acceleration. Contaminated fuel can cause a low O2S1 voltage during acceleration. When engine is idling or at steady cruise, O2S1 voltage should vary between about 100-900 mV. During power enrichment mode, O2S1 voltage should rise to greater than 446 mV. Also, check for malfunctioning or plugged fuel injector(s).

An intermittent condition may be caused by poor connection, rubbed-through insulation, or a broken wire inside insulation. Check PCM harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, or poor terminal-to-wire connections before component replacement.