Detection Condition

WARNING: This page is about a different car, the 2003 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

PCM monitors inversion cycle period, lean-to-rich response time and rich-to-lean response time of the sensor. PCM calculates average of inversion cycle period-specified inversion cycles, average response time from lean-to-rich, and from rich-to-lean when monitoring conditions are met. If any condition exceeds threshold, PCM determines circuit has malfunction.

Monitoring Conditions:

Calculation load 14-59 percent depends on engine speed (ATX)
Calculation load 20-59 percent depends on engine speed (MTX)
Engine coolant temperature is more than 14°F (-10°C)
Engine speed 1410-4000 RPM
Mode 3 - HO2S Heater, HO2S & TWC Repair Verification Drive Mode
Vehicle speed is more than 2.33 MPH

This is an intermittent monitor. (O2 sensor) MIL illuminates if PCM detects malfunction condition in two consecutive drive cycles or in one drive cycle while DTC for the same malfunction has been stored in PCM. PENDING CODE is available if PCM detects malfunction condition during first drive cycle. FREEZE FRAME DATA is available. DTC is stored in PCM memory.