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Discussion Starter · #1 ·
So I've had the "check oil" message showing up on my dash of my GT every time I start the car for the past couple of weeks. At first I thought maybe I was a quart low so I checked it on the dipstick and the level was fine. The next thing I did was change the oil as well as the sensor that's in the side of the pan. But still the "check oil" message comes up. The next thing I tried was changing the oil pressure sensor and screen on the back of the motor behind the intake manifold. I used all GM parts. But still I'm getting "check oil" on the instrument cluster. The oil pressure gauge on the center stack reads normal oil pressure. I have not tried to hook up a gauge to see what it's reading but maybe I should? Any other ideas on what could possibly be causing this? The car is 2008 model with 150K miles on it. Engine is stock with the exception of having DOD turned off through the ECM.
 

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Last oil change? Was the oil life monitor reset?
 

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Here's my take on this>>>>>

In my owners manual, they show a symbol that sorta looks like a tea pot dripping. They refer that as "service engine oil". That in fact relates to the OLS circuit "(oil life system) IF your "check oil" message is one an the same, It's detecting that the oil life monitor circuit "needs" to be reset. It should be performed "each" time your car gets an oil an filter change. If you fail to do that, the computer will continue with its OLM % remaining countdown.Once its reaches zero (from its 100% reset value), you get that warning symbol and I guess some wording display (I've never let that happen). They say it will remain at startup "until" you perform a reset.

If you feel that this may be the source of the problem, perform a quick reset. There are 2 ways to do it. One >>>> Turn on the ignition, press an release the gas pedal to the floor 3 times within 5 seconds, then turn the ignition off..If it reset correctly, the display should have extinguished on your next engine start run cycle.

If you want to see what the OLM % remaining countdown actually is, press an hold the left side scroll button while turning the ignition switch to the on position. Release the scroll button an start rotating it down until it highlights the oil life % remaining. From that you can press an hold that scroll button a few seconds, an watch the display jump to the 100% value. Doing that allows the car to start a countdown at from the 100% value with the current oil in the engine. Its easy to do, an "may" eliminate that annoying situation have. (or not)
 

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Discussion Starter · #4 ·
Thanks for the quick replies Pony & Gopherit. Just to confirm I changed the oil and filter (as well as the sensor in the side of the oil pan) a few days ago. I always use 5W/30 semi-synthetic oil along with Wix filters. I reset the OLM after the oil & filter change. I'm familiar with the "Service engine oil" message. This indicates when the oil is ready to be changed. But the "Check Oil" message is something different. This one is puzzling and a bit concerning. I hope I don't have an oil pressure issue.
 

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Seems you've thrown the parts cannon at the easy stuff. Maybe the warning light is legit. Getting a gauge on it may not be easy, but one way to validate or invalidate the electronic notification. Back of intake or oil filter housing may be possibilities.


Would be good to validate current cold start, cold idle, warm idle, oil pressure.

The L76/LS3 PCM has a representation of oil pressure psi or kPa from the sensor. A scan tool can display. Just captured this from my car.

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Other possibility is a partially clogged oil pickup screen, failed or failing oil pickup O-ring. Worn crank, rod, cam bearings can all be sources of low oil pressure.

The owners manual indicate the "Check Oil" message will continue to appear in the bottom of the DIC display until the vehicle has been serviced. Wondering if this means even if the condition is not currently present, the message will continue to display until the code is cleared.
 

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Per owners manual Check Oil refers to oil press or oil level sensor, when you scan it, look for P0521-523 if not set, pressure part is ok, replace level sensor pigtail, if 521-523 set replace oil press pigtail if all else (sensors and screen) were replaced
 
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Discussion Starter · #7 ·
Thanks for the response Thawk. I'm not getting any DTC's. But I put my scanner on the car anyway just to verify. I don't have a Tech2, just a basic scan tool. No codes came up and no pending codes either. Like you said, maybe I need to look into replacing the level sensor pigtail?

When I cold-start the engine the oil pressure gauge in the car is displaying 5 bars at idle (I think that's 30lbs) . Once I drive the car and warm the engine the gauge shows 1 or 2 bars (10-15lbs). Highway driving shows 5 bars (30lbs?). What kind of pressure do you guys see on your cars? I guess I'm concerned the oil pump is possibly failing and I need to park this thing before it's too late! I'm going to put a mechanical gauge on it and check the pressures to get a better idea.
 

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That sensor on the side of the oil pan is shown as a combination "low oil level" and "oil temp sensor". Can't find any good info yet, as to what "might" be displayed if it senses to high of a temp. The low level sensor portion states that "if" low level is sensed, it will display a message about the oil. The 3 wire connector says >>>>

Pin--- A (brown in color) supplies power to the switch/sensor
Pin---B (green/yellow in color) is the temp sensor signal
Pin---C (brown/red in color) is the low reference/ground wire.

The low level sensor/switch portion of that unit "must" show continuity when read with a meter going from A to C to keep the message extinguished. If you feel that the sensor/switch combo is OK, you could look for something like 5 volts dc on pin A to ground or pin A to pin C with the ignition switched to the on position. Pins A- B an C are hard wired to the ECM. Pin C is grounded within the ECM as well as the 2 wires supplied with voltage coming out of the ECM to the sensor/switch. You must have a good ground indicated with the meter going from pin C to a known good ground location. Anything missing (to me) indicates that a wire (or wires) have been compromised. If the "power or ground" wire has a problem, you would hope that its broken between the switch and the ECM. If not the ECM could be the problem.

If there is a wire problem, the car might be seeing and open switch condition, an that would force the ECM to display that message in the instrument cluster. Hope this makes sense if you want to T/S your car any more.
 

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You can jump terminals A and C for awhile and see if that stops the message as long as wiring ok, The B terminal is connected to C ground wire internal of switch through a thermister inside sw. to ecm for oil temp
 

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My understand is the E38 does not read engine oil temp, it's a calculated value. I mounted a remote temp sensor at the oil filter port and display both for entertainment as the PID temp value does not track external sensor during oil warmup at all.
 
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Discussion Starter · #11 ·
Finally getting back on this "check oil" issue. Thanks for the trouble shooting tips guys. As stated before, I wasn't seeing any voltage to any of the pins at the sensor. I got under the car tonight and decided to drop the starter so I could get a better look at the wiring harness that goes to the oil level sensor. As soon as I lowered the starter down the harness for the oil sensor fell to the ground! All three wires had melted and basically were disintegrated from exposure to heat. I think when I replaced the starter a couple of years ago I probably wasn't paying attention to how the wires are supposed to be routed and ended up placing the loom too close to the exhaust manifold. The wires for the knock sensor were pretty bad too (exposed bare wires!). Anyway, it's not going to be real simple making the repair because I can only get one hand up there. I started to pull the entire harness from the car so I could more easily make the repair but it's a fair amount of work getting the harness out. At least now I know what the issue is.... that's half the battle!
 

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Why not do it with the starter out, get both hands in there and fix it proper. You can make the wires as long as you need AND route them away from the exhaust. Removing the harness is a waste of time. (Crimp & Solder)
 
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