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Discussion Starter · #1 · (Edited)
I've been dealing with a code PO6DD for awhile now on my 2012 JK, and just thought I'd contribute to the vast amount of literature on the matter.

After spending weeks reading almost every thread on different JK forums on PO6DD, I came to the following conclusion. Legions of people, including those just purchasing a brand new JK, have struggled valiantly with this code. Dealerships have grappled and failed to fix the problem economically and effectively. Lone, beaten down individuals have sobbed into shop rags after spending the weekend replacing the oil pump and pressure switch solenoid, only to have the code sadistically pop back on five minutes into the first drive after the laborious install. Electrical connectors have been hunted down and inspected, wires examined, intake manifolds have been removed to get at the pressure sensor to replace it. And, sometimes, quite frequently from what I can tell, all to no avail. It appears that dealerships, reputable mechanics, and shadetree wrenchers like myself have spent countless hours to get at the enigmatic root of the PO6DD problem.

The real anxiety producer I suppose is the fact that the code has to do with your oil pressure. My year / trim level of JK doesn't have the wonderful EVIC with oil psi reading, which would have helped immensely. So not knowing the oil pressure, I did not want to drive my jeep with this code on, even though it ran fine. It did not have the symptom of going into limp mode after 3k RPM like some people have reported.

My understanding was that the "oil pressure control circuit stuck off" meant that the oil pump was stuck in high pressure mode, i.e that the solenoid's default setting is high pressure mode. But I didn't know for sure what was going on in those myseterious galleys. Was the engine getting an inadequate 5 psi or less oil pressure? Or was it above 100 psi, being all stuck in high pressure mode like my wife?

With all this in mind, I decided that the first step in dealing with the problem was determining what exactly the oil pump was doing. At least, I figured, if the oil pump was producing PSI that was in spec, that I could at least drive it while I endeavored over the months, maybe years, to hunt down the problem.

So first, I tracked down this: item Mopar part number 2021800090, Early Version 3.6 Oil Pressure Test Adapter. Note the price has gone up wildly. I saw some youtube videos from just a few years ago, with guys that got them for like 60 bucks. I got a deal on this one, from Freedom Racing (immediate shipping btw, good to deal with), for an eye watering $105.00. this was the least expensive one I could find after much digging. The very few other ones out there were over $120.00.

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And then basically installed a mechanical oil pressure gauge from NAPA:

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So what I found out is, the pressure ranges consistently from 60 psi idling when cold, then down to 25 psi at idle when hot, then to 40-43 psi at about 1200 RPM and up when driving at operating temp. I did not take it above 3500 RPM though, will do that later and see what happens.

I also hooked up a more accurate oil pressure gauge in the garage, got the same readings.

Overall I'm thinking this outcome rules out the oil pump solenoid as the cause of PO6DD. I would love to hear any else's perspective though if I'm off track.

One final note, I thought long and hard about the risks of putting in a mechanical oil psi gauge. I ran the line through the passenger side firewalI, where the big wiring grommet is. I was also extremely careful with the routing of the line to keep it off sharp edges and hot parts. Was thinking I'll probably just take the gauge out after awhile, once I see what the oil psi is doing over time.

Now I'm wondering what next to look into as a potential problem. I know the oil pressure sensor might be the next most likely part to replace.

I just hate though spending hours R and R'ing parts when I'm not sure if it's the problem. It does sound like that is what the majority of people have to do when this code persists, including dealerships and dilligent mechanics. Evidently, at least from what I can tell, there's no reasonable way to test either the solenoid or oil pressure sensor without removing them. At that point you might as well just replace them since you're in there and they're not all that expensive.
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