P0138
P0442
P0455

Pressure test makes sense now.
Thanks for the quick responses!

 

P0138 1/2 O2S Shorted To Voltage
P0442 Evap Leak Monitor Medium Leak Detected
P0455 Evap Leak Monitor Large Leak Detected

The first code is for the post cat O2 sensor.... seems either the wiring is shorted, or the sensor has failed internally, not really that much of an issue, as that one doesn't really effect how the truck runs. (but, it won't pass emissions that way, if that is a concern.)

Other two are EVAP system leaks. Check all hose/valves/cannister for leaks, bad spots, cracks, etc.

Neither of those two problems would account for funny sounding exhaust.... There is something else going on in there as well.

 

The p0138 is without a doubt a cat problem. Yes, it could be just the sensor itself (as it doesn't do much). But, it's telling you something. And in this case, I say clogged cat and blown plenum, etc...........

 

Excellent! So is the plenum usually the root cause for the cat and O2 failure?

 

Yes, and if you let it go too long, you'll crack the head(s) too.

 

The p0455 code is probably your gas cap. Take it off and stick it in a ziploc bag. Try and get as much air out as possible and seal it shut. Now carefully put it back on the truck and see if that code doesn't come back. It usually takes a while for it to come back. If it doesn't come back go and get a good gas cap(Preferably an oem mopar part, I had this problem and bought a cheap autozone one, And now 6 months later its doing it again).