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.

PCM monitors Heated Oxygen Sensor (HO2S) activity for 90 seconds after closed loop operation has been enabled. During this test period, PCM counts number of times HO2S signal voltage crosses rich-to-lean and lean-to-rich threshold, and adds total amount of time it took for all transitions. With this information, an average time for transitions can be determined. PCM divides rich-to-lean and lean-to-rich average to obtain a ratio. If PCM determines that HO2S ratio is not as expected, DTC P1133 will store indicating that HO2S is not responding as expected to changes in exhaust oxygen content.

When DTC sets, PCM illuminates MIL on second trip after fault was detected. Vehicle will operate in Open Loop fuel control. 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 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.