Circuit Description

Powertrain Control Module (PCM) continuously monitors Heated Oxygen Sensor 1 (HO2S 1) activity for 100 seconds. During monitor period, PCM counts number of times HO2S 1 switches from rich to lean and from lean to rich. PCM then adds amount of time HO2S 1 took to complete all switches. With this information, an average time for all switches can be determined. Whenever average time to switch is no within preset range, a DTC P0134 will set.