Test I
- When AIR pump is enabled, PCM monitors HO2S voltage. If HO2S voltages go below a threshold, PCM interprets this as an indication that pump is operational.
- When AIR pump is disabled, PCM monitors HO2S voltages. HO2S voltages should increase above a threshold and switch normally. If PCM did not sense more than a predetermined amount of HO2S rich switches, a malfunction will be reported.