DTC P1134 & P1154: Ho2S Transition Time Ratio - Bank 1 & 2, Sensor 1 (6.0L W/Isolated Ground): Description
WARNING: This page does not describe the selected car, but rather 11 other vehicles, including the 2002 GMC Yukon XL, 2002 GMC Yukon, 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, and 2002 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
This diagnostic applies only to vehicles built with isolated grounded Heated Oxygen Sensors (HO2S). The Powertrain Control Module (PCM) monitors the HO2S activity. During the monitor period the PCM counts the number of times that the HO2S responds from rich to lean and from lean to rich and adds the amount of time needed to complete all transitions. With this information, an average time for all transitions can be determined. The PCM then divides the rich to lean average by the lean to rich average to obtain a ratio. A DTC sets if the HO2S ratio is not within range.