What does dpe 33 means, i got that light on my 2003 nissan altima

Heated oxygen sensor curcuit -
This fault indicates a faulty O2 sensor or bad wire to that sensor.
It is a relatively cheap part - it bolts into the exhaust at the front of the car, you can see it between the engine and radiator, bolted into the exhaust with a cable running to it.
You can check this cable for security and make sure the connector is secure. it probably is faulty though.