DTC P0133: Ho2S1 Circuit Slow Response - Bank 1 Or DTC P0153: Ho2S1 Circuit Slow Response - Bank 2: Description

WARNING: This page is about a different car, the 2002 Nissan Xterra and 2002 Nissan Frontier. However, it is still accessible from the selected car via links, so may be relevant.

The front Heated Oxygen Sensors (HO2S1) are located in each front exhaust pipe, upstream of catalyst. They detect the amount of oxygen in the exhaust gas compared to the outside air. The front HO2S has a closed-end tube made of ceramic zirconia. The zirconia generates voltage from about one volt in richer conditions to zero volts in leaner conditions. The front HO2S signal is sent to the ECM. The ECM adjusts the injection pulse duration to achieve the ideal air-fuel ratio. The ideal air-fuel ratio occurs near the radical change from one volt to zero volts.

To judge the malfunction of HO2S1, this diagnosis measures response time of HO2S1 signal. The time is compensated by engine operating (speed and load), fuel feedback control constant, and HO2S1 temperature index. Judgment is based on whether the compensated time (HO2S1 cycling time index) is inordinately long or not.