Check engine light code help

Is there a way to get a code on my 2001 dodge quad? In past 2 weeks my check engine light is coming on for about 4-5 days then go out then come back on. I remember on older chrysler cars you could do the ignition on off, can this be done on the pickup? Truck seems to be running fine just wondering if it could be the gas cap sensor. If so where might it be located. I found how to get code and im getting code p0138 one of the 02 sensors. can someone tell me what location the 02 sensor might be and if this sound like the problem. Have been reading many different fixes for this and don't know what to do. Don't want to take to a garage for the repair would like to do my self.

thanks for the replys

P0138 is the downstream O2 sensor. I just replaced mine a couple of weeks ago. Its the one after the converter. Prices ranged from $50 to $110 around here depending if you get the direct replacement or the one you have to splice your old plug onto. A pain in the butt to break it loose but came out pretty easy.

I'm getting 2 stories in my search. My truck is a 1500 Quad cab 5.2l 4x4. The 2 different stories is that i might have 4 o2 sensors or 2 sensors. I haven't had a chance to look under the truck. If i do have the 4 o2s which side do i replace? The code is the p0138.

I know the 2 o2 sensors with the code i have is the aft of the converter. I'm a little puzzled if i have 4 need to know which one to replace or do i replace both aft o2 sensors?


Thanks

P0138 is bank 1 sensor 2. If you have single exhaust its pretty simple. If you have duals I am assuming that bank 1 is the passenger side because mine came up with that code on single exhaust. Sensor 2 is after the converter. Bank 2 sensor 2 would be codes p0157 thru p0161.