I understand what you mean. I talked to an engineer that used to work for Toyota, he says that the ECU is in another mode until the engine gets "hot." Once it gets to this point then it starts changing things. He said that GM wants the engine to get to its "hot" temperature as quickly as possible because that's where it's most efficient. He claims that the ECU will do everything it can to get the engine to that temperature including putting the 2 stage oil pump in high mode to increase oil pressure to warm it up more quickly. If you are running 205 and under your failing thermostat could be causing your computer to "flirt with being in warm mode" if that makes sense. That would explain why it is intermittent. Everyone I have talked to with a 4.3 and 5.3 said the temperature goes to 210 and then stays there and doesn't move... If it is at 205 and fluctuating at all I would say your thermostat is starting to fail. It's a very cheap part and very easy to replace, might be worth it. My oil pressure was high all the time before I replaced my stuck thermostat. It really never went under 50. As soon as I replaced it when it got hot, she dropped on back to just above 20 at idle. My code was coming back on every now and then but I figured out my oil was about 1.5 quarts low because I was always checking it on an incline. Filled it up to where it is supposed to be and haven't seen the check engine light since, I also put an AC Delco filter on at the same time, and a new oil drain plug(because the o ring was flattened where someone had over-tightened it and had slow leak), and filled the coolant reservoir back up where I lost antifreeze when I replaced the thermostat. I have heard people that had the P06DD and needed the oil pump replaced, however theirs was actually "stuck off" and their oil pressure was @ 70 all the time. Also another thing is the oil pressure sensor filter screen. I don't know if you have tried replacing the oil pressure sensor yet, but there is a plug about 3-4 inches back from it you take the plug out and there is a screen filter down it (you have to pull out with needle nose pliers) if it is dirty the oil pressure sensor can be getting the wrong readings and cause this code. I honestly think your problem is not the pump, its something stupid like my problem was lol. Also, do you have dexos 1 approved oil in it? Make sure it isn't the "high mileage" oil because it has extra additives that make it thicker, and a thicker oil can trigger P06DD by being the wrong viscosity. For example a 5w-30 high mileage oil is really similar to a 0w-40 is what I read somewhere. If you ask me these vehicles are getting way to sensitive, just like a woman, everything has to be just right. haha
I am dealing with this code P06DD, I would clear the code and when it switched to V4 mode it would immediately switch back to V6 mode and then give me a pending P06DD. I noticed my temp would never go past 180, my thermostat was stuck. Replaced it now it goes to 210 and the code disappeared.. for a little while. Now it comes back on at random every now and then. Seems like when I am accelerating hard. I am curious about what you said about your oil pressure though. You said yours stays between 45-55. Before I replaced the thermostat my oil pressure never went below 45, after I replaced it when the engine gets hot and I stop it will go on back to 20-30 range , and when I accelerate hard it will climb up to 60 sometimes past that. I was told that was the correct range of the oil pressure with this engine. You might have a thermostat that is starting to fail, what is your temperature like ?
Did you ever get this issue resolved?
So your oil pressure never goes below 40 on your 4.3? I had the code P06DD which is very similar to the one you had. My problem was the thermostat was stuck open and temperature was never going above 180. Once I replaced it the temp went up to 210. Before I replaced the thermostat my oil pressure stayed about 40-45 at idle and went to 60 and a little over when accelerating. Now it idles about 60 on cold start up, comes back down to 40-45 a few minutes after start up, but once it gets hot the oil pressure drops on back to 20-30 at idle. My pressure goes past 60 near 70 when I accelerate. I was told that was the correct range for this truck that if it was never going under 40 psi when it was hot that there was something wrong. This fixed my issue for a little while, now I find the code coming back every now and then as a pending code. Before I replaced that thermostat every time my truck went into v4 it would immediately switch back to v6 mode and throw the pending code. Now I have drove over 500 miles with it going into V4 mode like it should, but sometimes (seems like its when I'm accelerating and the oil pressure is over 60) it will stop going into V4 and I will see a pending code P06DD and I clear it out, and then I won't see it for a while. If yours is never going past 60, makes me wonder if that's what is causing my pending code when mine goes past 60 psi. I know its been 4 years since you posted this but hopefully your still around on here
Well I replaced the thermostat, and drove it down the road and back, and it went up to 210 and stayed there. Also my oil pressure dropped back to about 40 cruising, and down to 20-30 at a hot idle. Haven't seen the Check Engine light back on yet, so I am hopeful!
Ok, I am going to pick up a thermostat on the way home from work today and see what that does. The scanner I have is just a Bluetooth obd2 reader and I don't see a temperature or oil pressure readout on it.. it just gives me P06DD code... I can reset it and it and drive the truck and it will go into V4 mode a few times then will stop going into it. I can check it after it stops going into V4 mode and there will be a pending P06DD code. My temperature never gets past 185 and most of the time is lower than that. My thinking is that if the oil pressure changes from 40 to 60 then both oil pressure modes are working, but the overall oil pressure is higher than normal in both modes. I know oil is thicker when it's colder and will cause more oil pressure. I am hoping my tstat is stuck open causing it not to fully warm up, and once that's fixed my oil pressure will come down some into the range acceptable to the computer. CamGTP says that the oil pressure should come on down to 20-30 psi when hot. Is that what the 5.3 oil pressure is? I noticed that the 5.3 uses 0-w20, the 4.3 uses 5w-30 and maybe the 4.3 oil pressure runs a little higher because of the thicker oil? I don't think the 20 or so degrees of heat I will gain will bring the oil pressure down that much. I guess it's wishful thinking that the two problems are related, but I guess I will find out if the thermostat fixes the temperature problem. I appreciate y'all's responses!
I just noticed today that my engine temperature does not go past 185, and is sometimes lower. So I am guessing my thermostat may be stuck? If the oil is never getting hot then my oil pressure would be staying high and maybe be causing my code? Thanks
Ok thanks! Do you think that means that the oil pump is just stuck in high pressure mode all the time? I guess the only way to know is to take it to a mechanic that can switch the solenoid back and forth and see if it changes right? Thanks for the response!
I have a 2014 Silverado 4.3l 4x4 lt , I recently bought this truck and the check engine light came on P06DD. The oil was very dirty so I changed it and the filter, however the CEL came back on. I ran that oil for a couple hundred miles and replaced it again to make sure all that old sludge mess got cleaned out of there. Seems doing that helped prolong the time that it took for the CEL to return. I replaced the oil pressure sensor, but it did not change anything. I used an OBD reader and noticed that after I reset the code and I drive it the truck will go into V4 mode a few times then won't do V4 mode anymore and then I will have a pending P06DD code. The oil pressure runs just above 40 when idling and goes up to 60-70 when accelerating, however at cruising it hangs around 60. I would expect it to be back down around 40 when in 6th gear and running at a low rpm, but that may be normal. From what I understand there is a 2 stage oil pump and the solenoid switches between low and high oil pressure mode. That fact that it has a range of 40 to 70 oil pressure makes me think the solenoid is working. I called a dealership and talked to a service guy and he said that sounded normal. I would love to talk to someone who has a 4.3 and could tell me how their oil pressure works, or anyone that could help, thanks !
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