Testing (DTC) P0135: HO2S 11 Circuit Malfunction can be done without any expensive diagnostic test equipment, all you'll need is a multimeter.
A trouble code P0135 signals a problem with the internal heater of the upstream oxygen sensor.
In this tutorial, I'll show you the 3 basic tests you'll need to perform to diagnose the front oxygen sensor.
The front heated oxygen sensor (HO2S 11), on your 4.7L V6 equipped Dodge Dakota (or Durango) is a 4 wire oxygen sensor that has an internal heater.
2 wires are for actual oxygen sensing part of the sensor assembly. The other 2 are to supply the heater with power and Ground.
NOTE: You can find the location of the front oxygen sensor (HO2S 11) here: Location Of The Oxygen Sensors.
Below, you'll find the color of the wires of the engine wiring harness oxygen sensor connector for sensor HO2S 11: