Circuit Description

WARNING: This page is about a different car, the 2000 Isuzu Rodeo and 2000 Isuzu Amigo. However, it is still accessible from the selected car via links, so may be relevant.

Three-Way Catalyst (TWC) system is used to control emissions. PCM uses signal from rear Heated Oxygen Sensor (HO2S-2), located behind TWC, to read efficiency of TWC. PCM will set DTC P0140 if HO2S signal voltage remains between .4-.5 volts for an extended period of time.

Conditions required to set DTC are:

No related DTCs set.
Engine running time is longer than 2 minutes.
HO2S-2 heater is operating properly, and HO2S-2 is at operating temperature.
Engine is operating in closed loop.
HO2S-2 signal remains between .426-474 volts for 106 seconds during a 125-second period.