More Fault Codes, p0107, p0138

Buddy of mine has a 98 XJ (I believe its a 98). He was driving along the other day and his CEL came on. Pulled into Autozone and had the codes pulled. He lives in Utah, I live in AZ (although im currently in Wyoming wondering if my truck is about to get blow onto its side) so I didn't get a chance to look at it. I will list the 2 codes below, any chance its just a shorted out 02 wire or more?

p0107 - Map Sensor Voltage Too Low - MAP sensor input below minimum acceptable voltage.

p0138 - 1/2 O2 Sensor Shorted To Voltage Oxygen sensor input voltage maintained above normal operating range.

Code info from http://www.stu-offroad.com/engine/scancodes.htm

Thanks

Are there any driveability "symptoms" going along with those codes?

By these code numbers, there is a "possibility" that there is more than one thing going on here.....

My strategy is to always deal with them one by one, starting with the lowest code number (normally). That would be the code for the map sensor. If you resolve/fix the problem with the first code, try clearing the codes and see if any codes return.

The map sensor can be tested with a meter and a manual. There is a vacuum line going to the map sensor so be sure that vacuum line is intact and working properly before even testing.

The P0138 could be the oxygen sensor itself. (downstream sensor after the catalytic converter) Here is a link to some more info on that code.

http://www.obd-codes.com/p0138