Hello! I'm new here but my problem sure isn't lol, 2 years ago I bought a 2003 Dodge Ram 1500 quadcab 2WD 3.7L v6 with 149000 miles from a dealer in town. When purchased the dealer said "just needs an o2 sensor" which is code for has 12 more hidden trouble codes AND needs an o2 sensor :/ so those were all fixed at my cost, new upper and lower NTK oxygen sensors and a new Magnaflow catalytic converter (my truck only has the 1 cat and 2 sensors) plus a host of other new parts and for a year I had NO check engine light. About 4 months ago it popped back on one day with P0141 "Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2" so this time I replaced just the downstream with a new Denso sensor from RockAuto. CEL cleared annnnd 2 days later P0141 AGAIN! So this time I checked the ohms on the new downstream sensor and the sensor had a reading of 7.1 ohms, well within the spec for a new downstream o2, aka the sensor is fine and working. Today I scanned the truck again because I really need to get this fixed and now I have 3 codes! (P0141, P0138 and P0442). So why the CEL? Is there something else that can go wrong on these trucks besides the actual o2 sensor itself causing a P0141? Wiring maybe?

Truck runs great, starts right up, smooth idle at 750RPM so I'm really stumped here , any help in the right direction is greatly appreciated! Thanks! - Jimmy