My 02’ ram 1500 (4.7 w/ 320k mi) is acting funny lately. It’s getting sluggish at low speeds/low rpm and gets stuck in limp mode (2nd) when cruising between 30-45mph. Doesn’t have issues in third or fwy speeds. Also fast acceleration through gears doesn’t seem to act up. Sometimes it will clunk into limp mode, and lately it sneaks into it more smoothly. Only codes I get are P0420 and P0700. They happen simultaneously with the issue (reset codes, and came back simultaneously again). I was hoping it was a cat problem, but temps are normal. O2 sensors are fairly new and t-fluid level is good and clean. Any experience with this issue would be helpful. Not sure whether I should be looking at sensors, PCM, TCM, trans solenoid, or other.

perhaps related or could be unrelated, around the same time it started I noticed a whistling noise when not on the gas. Starts high when I let off and gradually lowers. Once I apply gas, it goes away. I had a pressure/smoke test done last time it was in getting crank/cam sensors replaced and they couldn’t find anything.

 

Check here for the P0420 code... Too many possible causes there to list. The other code is just a generic transmission code, which is supposed to be accompanied by another trans code, that indicates what the real problem is. Given that both codes show up together, I wouldn't be surprised if there wasn't a wiring issue to that O2 sensor, and it's taking the trans with it..... See if they have anything wiring related in common wouldn't be a bad start.

 

Thanks for the reply. You mentioned “that o2 sensor”, any clarification on which?

 

Post cat O2. The "here" was supposed to be a link, but, I seem to have forgetting to actually LINK it..... Been a long week..... Yeah, yeah, that's it. A long week.

Try having a read here.