Hi all,
My check engine light has been popping on and off for the last couple months. It seems to come on at random times and then turn off a few hundred miles later. The truck runs fine, it just seems to be a little rough at idle, but not too bad.

The code is "P0138 o2 sensor 1/2 voltage too high" or something like that. My question is, will this cause idle issues? Will replacing the o2 sensors fix the problem? My plenum gasket is fine and I already replaced the cat with a direct fit magnaflow cat. What o2 sensor it throwing the code? Thanks in advance.

 

Replacing the O2 will almost definitely resolve your issues. It's generally recommended to replace them as a set.

 

yes the 02 sensor will cause idle issues (pre-cat sensor)

and what he said

 

Thanks guys, looks like the auto parts store will be getting a pretty good chunk of my paycheck tomorrow. Oil + filter, a wheel bearing, and now 2 new o2 sensors. Great.