OBD-II Trouble Code Description for P0134 Subaru

O2 Sensor Circuit No Activity Detected

What does this mean?

OBD2 Code P0134 Subaru definition:
This code definition: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 Subaru code.

Symptoms

Possible sumptoms of OBD code P0134 Subaru
One or more of the following may occur: Check engine light illumination Poorly running/engine missing Blowing black smoke Poor fuel economy Dying, stuttering

Causes

Possible causes of OBD code P0134 Subaru
A code P0134 Subaru may mean that one or more of the following has happened: Bad O2 (oxygen) sensor Bad heater circuit in the O2 sensor Wiring or connector to the sensor frayed / broken Blown heater circuit fuse Holes in the exhaust system PCM failure

Possible Solutions

The most common fix is to replace the oxygen sensor. But that doesn’t rule out the possibility of: Rusted exhaust pipe Inspect wiring & connector(s) for problems Excessive amperage blowing heater fuse (still requires replacement of sensor but also replacement of blown fuse) Replace PCM (only as last resort after all other possibilities are covered.