I have problems with my O2 sensors. Mine is a 2000, ram 1500. It has two O2 sensors and there aren't voltage in any of those. Fuse is fine. I checked the fuse box and shows in the label, two relays, for the O2 sensors. Those relays are not installed on my fuse box. Are they supposed to be installed? There is not conections in those relay's slots,I mean they are empty.

 

somebody knows???? plz..

 

Nobody knows???

 

..... There shouldn't be any voltage applied to the O2 sensors. The relay and fuse apply voltage to a heater inside of the O2 sensors so that the PCM can go into closed loop faster. I would imagine that if the heaters wern't working the O2 sensor still would. The O2 sensor actually creates it's on voltage depending on the amount of oxygen in your exhaust. The PCM then adjust the fuel mixture based on those readings. The heater inside of the O2 sensor heats the O2 sensor up while the car is warming up so that the PCM can start using it. With out the heaters it will take longer for the O2 sensor to heat up since it has to wait for the exhaust tempurture to rise. Do you have a CEL on? Why do you think you have a problem with the O2 sensors?

 

I'm also curios why you think they are bad. If you want to test them you can unplug them and put an ohm meter across the two white wires and they should be in between 4.5 to 7 ohms. This will test the heater.

 

It should be 12V during the first two seconds when you turn on the start switch. If you don't start the car, this voltage disapears. I don't have any voltage at the beginning.

 

This will test the sensor itself. I have one good (5.1 ohm) and the other looks bad, but the scan tool shows both with problems.
If you don't have voltage or communication between the sensors and the PCM, even if they are good, they won't work.

 

For a Dakota when your starter (engine cool, lean mixture and high oxygen ) the voltage is 0.1V and 0.9V (rich mixture and poor oxygen)