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- - Low Oil Pressure warning (https://chevroletforum.com/forum/tahoe-suburban-25/low-oil-pressure-warning-41924/)

08 Suburban 1500 LTZ low oil pressure warning

Ok I am having the same problem with the low oil pressure warning light and check engine light coming on as others are. I have an 08 Suburban 1500 LTZ 6.0L 4 wheel drive with 112,000 miles. Never had this problem until now. Oil gauge started bouncing around then steadily began dropping eventually setting off warning. Stopped checked oil, it was full. Started back up pressure was back up. Drove it & within a few miles started dropping again. Took it to a friend who owns a shop and is an ASE certified master mechanic. He replaced the oil pressure sending unit. He said he wasn't charging me until we saw if that solved the problem. It worked for one day then the same thing. Well I had to take it to the dealer to get the door handle fixed so I had them check it out. They just called and said it was the oil pressure sending unit and was going to be $700 to fix. First I said I just had that replaced last week and second I said $700? The GM service guy said well we show that is what the problem is and the part alone is $600. Needless to say they are not fixing my vehicle. I called my mechanic friend and told him what the dealer said. He told me the OE GM part is only $86.24 and list 3.6 hrs labor. Thanks a lot Tyler Motors for trying to screw your customers, I bought this vehicle from you, I am going to trade it in for a Ford.

Maybe not the sensor....

My Suburban's low pressure warning scenario occurred again last month. This was after replacing the sensor with the oem part (described earlier). My gut now tells me that the sensor may not have been the culprit behind the low pressure reading after all.
I've recently come across discussions regarding low oil pressure readings for Suburban's, Tahoes and others sharing the same engine. One of these many discussions can be found here.
Apparently there's a small internal filter called a valve lifter oil filter just prior to the pressure sensor. This filter/screen is prone to develop sludge/oil deposits over time*. It can accumulate to the point at which the sensor returns low or no oil pressure, when in fact the top and bottom end pressure is in the normal range.
I suspect that this is what's going on in some instances when a newly replaced pressure sensor seemingly fails. It would also explain why the behavior of the sensors in some cases appears to be pressure-related and not an electrical fault, and why an oil change seems to revive the pressure to a normal level, sometimes only for a relatively brief period.
Per the service bulletin, the labor required to remedy this lifter oil filter blockage involves removing the valve cover(s) at the very least. I suspect it's costly labor-wise.
Since I have no desire to turn my Suburban over to the dealership and likey pay for misdiagnosed repairs like another sensor, I decided to try a crankcase additive that would go after this sludge - in an attempt to clean this filter/screen. What would I have to lose?
I'm familiar with Seafoam and the results that I've had when used to clean intake systems. However I'm not familiar with its results when used in the crankcase, so I used it conservatively.
I decided to pour a pint directly into the crankcase 300 miles before the needed oil change. I have to assume that any solvent-based cleaner/detergent significantly reduces an oil's viscosity and therefore shouldn't be left in the crankcase for an entire oil change interval.
After 100 miles, the pressure reading was back at 1:00 on the gauge - in the normal range. After 300 miles I changed the oil - this time to a synthetic. The pressure has remained normal since then.
I'm now convinced that this is a sludge/deposit issue - not a sensor issue....at least in my case.
Eric, I understand your frustration here. I've owned many Fords, and they're not perfect either. Since you've already replaced your sensor, you should take a look at the bulletin that I refer to above and share it with your mechanic buddy. Let him advise you on the Seafoam treatment considering that there's at least one positive result from it. He may have an entirely different opinion than I do. Even if he's concerned about engine wear, if you're seriously at the point of trading this vehicle in, why not try to revive the pressure reading using this cheap, DIY method. If it works for you, you'll get much more for it at trade-in ;)

*I've used non-synthetic in my 160k Suburban, as did the previous owner. The oil and filter has been changed per the vehicle's change interval that's based on the types of driving - not simply miles. I have to think that using conventional oil - not synthetic, and changing it over extended periods, like 7,500 miles or more, is the cause for this sludge buildup.
From this point on, I will now use full synthetic due to its lower deposits, and will be changing the oil and filter more frequently than the interval computer indicates.

UPDATE - 7/17/17:
3 1/2 years after this post, and 80k more miles on the odo (now at 220k) I've been routinely using synthetic or at least a synthetic blend at the change intervals per the computerized oil change counter. I opt for any preferred brand of filter.
Most importantly, I've been adding a pint of Risolene Engine Treatment about 100 to 200 before the oil change as an aggressive purge of the buildup of any sludge or deposits in the crankcase - specifically at the oil sensor screen. Probably unrelated, but the truck gets a bottle of Chevron fuel injector cleaner added to the gas tank every 4th or 5th fill up.
I haven't experienced the low pressure issue - or low pressure readings now for 3 1/2 years and 80k miles, since I started this regimen and stopped using conventional oil for my oil changes.
The proof is in the pudding.
UPDATE - 1/11/18:
With about 18% left on the oil change counter, I got a low pressure reading and the 'low oil pressure, stop engine' warning. This time a quart of Risolene and 100 miles didn't fix it/clean the filter.
So I decided that it was time to replace the oil pressure sensor filter (GM part 12585328). It's a $7 part, but replacing it is the difference between the sensor throwing a fault and eventually a CEL code and a properly working sensor.
Today was a warm enough day to do the job, so I took it on with complete success. I'll post a DIY thread on this forum and link it here.

Quote:

Originally Posted by JPTL (Post 265277)

Thanks for the info JPTL I will look into that. I believe the clogged screen may be the problem. I changed the oil and the problem has seemed to resolved for now. My biggest complaint is with the dealership trying to rip me off. Told me 700 fix, went up there to get it writing then it became a 580 fix. Called a competing chevy dealership and said it was a 300 fix.

Eric, If changing the oil had any effect on the pressure reading, my guess is that the new sensor is fine. If you give your new oil 1,000 miles or so, pour in a pint of Seafoam, run it for 100 or 200 miles and change, you might get lucky and see your pressure reading return back to normal like I have.

I believe that most if not all dealership service centers follow the factory shop manual for repair estimates. When it comes to accessing/replacing the sensor, the factory shop manual calls for removal of the intake. There are undoubtedly several labor hours involved in that....certainly more than the reach-around-back method mentioned in this thread ;). I agree that $700 is a gouge, especially if they have a tech who knows how to replace it via the reach-around-back method. But don't let this experience with your Suburban and that particular dealership sour you from the Suburban. A similarly aged Ford Expedition has its quirks as well, and there are also questionable Ford service writers out there.
Good luck with this.

I have to agree with JPTL, I think all of his points are spot on... I too have read that the screen blockage can be the cause of the low pressure reading....I have an 07 with the 5.3L and have only run M1 full synthetic since day one... I currently have 91,000 and have not had any low pressure readings..

I have a 2007 Chev Suburban 1500 4WD and just got this CEL and message last week. The pressure starts at about 40-45 psi on startup and drops to 5 or so after warmup. It has consumed 1 quart every 1500-2000 miles since it was new. I've always run 5W-20 mineral oil but after reading this forum am going to switch to full synth...right after I try this Seafoam procedure for a hundred miles or so. Wish me luck!

Quote:

Originally Posted by Eric Banks (Post 265630)

Keep us posted!

Quote:

Originally Posted by oldchevyguy (Post 238584)

Update changed oil and filter problem gone. I suspect there is either no bypass on the filter or it is not working. Guess I'll just keep filter changed more regulary and stop using oil life percentage. Thanks

Same exact symptoms with low oil pressure. Oil level was also fine but low. I added a quart of oil and was able to drive maybe 15 minutes before the oil pressure started dropping again but stayed above 15- 20 psi. What the hell, changed the oil and filter( upgraded to a mobil 1) and wouldn't you know the oil pressure problem disappeared. 60 psi on initial start and settles in at 40-45 psi. which is where it normally runs. Oil service indicator was about 19% . Outside temp was above freezing. Certainly hope this resolved my problem.

Low oil pressure

I changed my low pressure oil sensor and the problem was still there. So I flushed the engine oil with a flush kit and changed the oil once I was done and the problem went away. It’s seemed that there may be some dirty oil obstructing the proper oil pressure flow. All I can say it worked for me and that was the best 6 dollars I spent for this repair.

Quote:

Originally Posted by JPTL (Post 265692)

Keep us posted!

Quick Update: I added a can (pint) of Seafoam last week and immediately saw an increased in the (indicated) oil pressure, about 10-15 psi. (It had been right about 40psi at startup and the Seafoam increased it to around 50psi.)

I drove for about 15 minutes and the pressure stayed up around 30-40psi. I put about 50 more miles on with no issues.

The next day, I started it and the pressure was normal but, much to my dismay, dropped down to about 5-10psi after 10 minutes, triggering the alarm again. I found a place to pull over, shut it down for a minute or two, and restarted it; pressure back up.

I drove around for the next week putting about 141 miles on the Seafoam then changed to Mobil 1 and a new filter yesterday. Pleased to report the pressure is up to about 55-50 on startup and hovered around 40 the rest of the day.

At this point it looks like my problem is solved! Thanks so much for sharing this information!