OBD-II Trouble Code Technical Description
O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)
What does that mean? This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles. Although generic, the specific repair steps may vary depending on make/model. This code refers to the front oxygen sensor on Bank 1. Basically the oxygen sensor is inactive. Here’s why: The powertrain control module (PCM) provides a baseline voltage of about 450 mV on the oxygen sensor signal circuit.
When cold, the PCM detects the the internal resistance of the sensor is high. As the sensor warms up the resistance is lowered and it starts producing voltage based on the oxygen content in the exhaust. When the PCM determines that the time it took for the sensor to warm up is greater than one minute or that the voltage is inactive (not reading outside 391-491 mV it views the sensor as inactive or open and sets the P0134 code.