Circuit Description

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.

To provide the best possible combination of driveability, fuel economy and emissions control a "closed loop" air/fuel metering system is used. When vehicle is first started PCM controls fuel delivery in "open loop mode", ignoring HO2S signals and calculates air/fuel ratio based on inputs from the ECT and TP sensors. DTC P0125 sets when a stuck open thermostat or other cooling system problem occurs, causing engine to not reach normal operating temperature is detected.

When DTC sets, PCM illuminates MIL on second trip after which fault is detected. PCM will store conditions present when DTC was set as freeze frame data in the FAILURE RECORDS data.

PCM will turn MIL off on third consecutive trip cycle during which diagnostic runs and fault is no longer recognized. A history DTC P0125 will clear after 40 consecutive trip cycles during which diagnostic runs and fault is no longer recognized. DTC can be cleared with scan tool, or by disconnecting battery voltage feed to PCM.