DTC P1134 & P1154: Ho2S Transition Time Ratio - Bank 1 & 2, Sensor 1: Description
WARNING: This page is about a different car, the 2002 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.
The Powertrain Control Module (PCM) monitors the Heated Oxygen Sensor (HO2S) activity. During the monitoring period the PCM counts the number of times that the HO2S responds from rich to lean, and from lean to rich, and adds the time used to complete all transitions. With this information, the PCM can determine an average time for all transitions. The PCM then divides the rich to lean average by the lean to rich average in order to obtain a ratio. If the HO2S ratio is not within range, a DTC will set. This diagnostic runs once per ignition cycle.