00XJ O2 Sensor Question

[y2kxj]

My 00XJ's check engine light is on. Ran the scan tool and came up with Left Bank Downstream or Downstream and Pre Catalyst O2S Shorted to Voltage. The code was a P0138 Oxygen sensor input voltage maintained above the normal operating range. Any ideas as to what this means?

 

[XJNick]

Pre Catalyst O2S Shorted to Voltage. The code was a P0138 Oxygen sensor input voltage maintained above the normal operating range.

The 02 sensor works like most all the sensors in that it receives a set input voltage from the Powertrain control module (PCM) and then varies resistance according to 02 levels to produce a lower voltage to the PCM.

It sounds as though your 02 sensor (the one installed BEFORE the catalytic converter) is shorted so as the computer is receiving it's full ouput voltage to the 02 sensor in the sensor's return line to the computer (i.e. the 02 sensor is creating little or no resistance and is not functioning).

Check the wiring for shorts, if none are found, replace the sensor :mrgreen:

-Nick :!: