I have a 1994 Dodge Dakota 2wd 6cyl with about 150,000 miles.I'm getting the check engine light. I checked the code and got 21 (Oxygen Sensor). My question is how do you know which oxygen sensor it is (before cat or after cat)? Or should I just replace both?


2nd question:

The Ac never really worked in the truck. Thats not the problem tho. When I have all the controls off on the Ac/heating control and I'm driving it feels like the vents open. I'm getting nothing but hot air in the cab. Its only when driving. Is that normal or is something stuck open?


Thanks

 

There should only be one. 96 and up should have two. Yours will be befor the cat.
The air coming in throgh the vents is normal. The air for the system comes from outside. The best thing to do is turn on the fan and put it to hot (it may be cold im not sure) Then turn off. It shouldnt come in anymore.