Engine light warning code P06DD question

Question

2019 Tahoe and the check engine light came on. Diagnostic code P06DD which gives me “engine oil pressure control solenoid valve stuck off” I have an appt with the dealer in 2 weeks. They are really backed up. In the meantime though the check engine light has gone off. Can this issue resolve itself? Is it safe to drive the vehicle until my scheduled appt?

Answer 1

Bottom line, if the light went out, it's probably okay. The CEL has to do with how the oil pump works. There are two modes: high and low pressure. Here's the write up on it from obd2-code.com:

... the engine oil pump features seven vanes and a moving element that continuously adjust to maintain a regulated oil pressure supply by varying the displacement of the pump. The pump has two regulated pressure stages of operation controlled by an on/off solenoid. Low pressure mode regulation (solenoid on) is approximately 200 kpa (29 psi) and high pressure mode regulation (solenoid off) is approximately 450 kpa (65 psi). The Powertrain Control Module (PCM) switches the pump between stages based on engine operating conditions, oil and coolant temperatures, speed and load. Under most typical conditions, the pump will run in low mode from idle up to around 3000 rpm and switch from low to high mode between 3000 and 4000 rpm. The maximum oil pressure in the engine is limited to 1000 kpa (145 psi) by the relief valve. Pressure in the main oil galley of the engine can be monitored with diagnostic equipment through the oil pressure sensor. The minimum pressure for the engine is 41 kpa (6 psi) at any operating condition. Anything under this pressure could result in damage to critical moving part.

Considering the code is for the solenoid being stuck in the "off" position, it means you'd be getting higher oil pressure than it normally would at lower engine speeds. This really isn't an issue. I believe the main thing the engineers were trying to do here was to allow the engine less oil pressure at low speed so there'd be less drag on the engine, which will allow for lower fuel consumption.

If this was stuck in the "on" mode, you'd only get the lower pressure. In that case, I'd suggest it could be an issue because when the engine needed the higher pressures, it wouldn't be getting it. I don't think it would kill an engine, it just wouldn't be good for the engine. In your case, I don't think it would cause any issues other than possibly a little less fuel economy.

Answer 2

We had this problem in our 2014 GMC Sierra pickup. It is 4WD so to replace the oil pump and solenoid, the Transaxle had to be dropped. We came up with another solution that absolutely solved the problem. It costs $40.00 and an oil change. I will give the description and then the step by step. The solenoid for the oil pump is either getting stuck, or there is a clog/clot in the passage way. The varnish or clog must be cleaned for the solenoid to function. We cleaned it without taking the components apart. I will get some grief for this, but it worked, it saved us over $2500.00 and it only took a couple of hours. We drained the oil from the oil pan, took the oil filter off. Filled the oil pan with Lacquer thinner(6qts), turned the engine over and catch the crud under where the oil filter was, drain the rest of the lacquer thinner, replace with new oil, new filter and within 50 miles or so, we had success. Step by Step Drain Engine Oil Put plug back in Remove Oil Filter and put pan under vehicle there Fill through crankcase dipstick tube, 6qts of Lacquer thinner. DO NOT POUR INTO NORMAL OIL FILLER CAP. We want to keep the Lacquer thinner in the Oil Pan ONLY because it may swell natural rubber parts like valve seals. Remove the fuse box cover. Find the starter relay(upper left standing at fender). Make a small jumper wire and jump the starter relay using diagonal pin holes. DO NOT USE THE KEY TO TURN OVER THE ENGINE. THIS WILL CAUSE THE IGNITION TO BE ENGAGED AND THE ENGINE TO RUN. YOU DO NOT WANT THE ENGINE TO START and IGNITION MAY EXPLODE THE Lacquer Thinner FUMES. Turn engine over for 10 sec, wait 20 sec, and repeat about 10 times. You will notice that the lacquer thinner is being pumped out of the oil filter housing into your collection pan.
Drain the remaining Lacquer thinner. Notice the lumps of crud coming out of the oil drain hole. Add a bit of new oil to the normal fill point to flush out any lacquer thinner that is in the pan. Put the oil plug back in. Fill the crankcase with normal amount of oil. Turn over engine using jumper until oil comes out of filter housing. Put filter back on. Top off oil. Put Start relay back in. Run your engine using the key. Within 50 miles, our Engine light went out, The oil pressure would change( it was always too high before) and it would go into V4 mode once again. After that, we put 1/2 can of Sea Foam in the oil pan with the oil changes. We have not had a problem ever since......$40.00 in Lacquer Thinner at Lowes. NOTE: This can be dangerous if not done the way that I have listed. Also, you must be aware that you are turning your crankshaft with the starter with no additional oil to the bearings while cranking. The alternative is to take 1/2 of the engine apart to fix this anyway, so we thought that we had nothing to lose. We have since gone over 500 miles with no codes and perfect oil pressure response.