Low oil pressure on DIC, check gauges light and oil pressure gauge is low

[Steevo]

I have been getting occasional Low Oil Pressure messages on my DIC, combined with a check gauges light. When this happens the oil pressure gauge is low.
This only happens at idle, like at a stop light.
I noticed the engine stumbles slightly, and pushing down on the throttle resolves it.
It all straightens out immediately. It might not reoccur for days.
The oil level in the crankcase is normal.
There is no associated clattering noise of valves and lifters that is normally found with an actual low oil pressure situation, so I think this is related to electronics.
There is no code in the ECM.
I asked a friend and he said he doesn't think it's actual low oil pressure, because you'd be able to hear it. He saw the problem occur.

Can anyone point me to what to check out? The vehicle has been running well.

 

[Dr.Fiero]

Get someone with a gauge (manual) to check it "for real". A t-fitting will have to go in, so you can compare the dash reading to the gauge.
Hopefully nothing more than a bad sender. Have had to replace tons over the years.

Even scored a killer deal on a Chevy van once, because the seller was convinced it had low/no oil pressure. Someone put a 'gauge' sender into it, when it only had an idiot light!

 

[mrrsm]

Frankly... This sounds more like a problem with a Dirty Throttle Body that is sticking enough to cause a near stall below 600 RPMs which would certainly drop the Oil Pressure to sub-nominal levels. However... Better Safe Than Sorry:

First… Understand that this is very big problem if it turns out to be something other than an inoperative Oil Pressure Sender... or 'sketchy' Oil Pressure readings from your Dashboard Gauges. To do this job safely...you will need an adapter that is NON-SAE, NON- NPT AND STRICTLY METRIC to screw into the threaded hole presently occupied by your Engine Oil Pressure Sender. It is located on the Front Passenger side of the Engine Block in the Manifold just above the Screw-In Oil Filter Manifold. The one listed below is 16MM X 1/8th" NPT and should do the trick. Do not use excessive force or Over-Tighten the Adapter as your engine block is All Aluminum and easily damaged:

https://www.ebay.com/itm/LS-OIL-PRESSURE-Adapter-Short-Version-1-8-NPT-x-16mm-/173046202417

Then you will need a decent Oil Pressure Gauge Tester Kit to attach to the above Adapter temporarily until you can check out your Oil Pressure at various RPMs ... BEGINNING WITH A LOW IDLE TO ESTABLISH YOUR BASELINE OIL PRESSURE TO BE AT LEAST 12 PSI… If you cannot see Oil Pressures at idle above or equal to that base line… You can suspect either you have a completely clogged up Oil Pick Up Screen-Tube in the bottom of your Crankcase… or your Oil Pick Up Tube-to-Gerotor Oil Pump Sealing Grommet has failed where it seals between them. If this has occurred… You will have lost the Oil Pump Prime inside of the the Gerotor Oil Pump Gears and fail to achieve nominal Oil Pressure (THIS is Very Unlikely to have happened and would be VERY RARE since your Engine has the Later Model Design of this hardware). This OPG Kit is not too expensive and should do this job nicely:

https://www.amazon.com/8milelake-Engine-Pressure-Tester-Diagnostic/dp/B01N98909D/ref=sr_1_11?s=automotive&ie=UTF8&qid=1515635135&sr=1-11&keywords=oil+pressure+gauge+1/8"+npt+kit

If, however your Oil Pressure(s) remains nominal throughout all ranges of RPM… but the Oil in the Crankcase is BLACK… Then change out your Old Oil and Old Oil Filter using inexpensive Organic Motor Oil, an Inexpensive Oil Filter ...right along with One Quart of any decent Engine Flush to run the motor AT IDLE for only around (5) Five Minutes. Then, immediately change out your Oil and Filter once again ...and use Mobil1 Synthetic Motor Oil and a Mobil1 Oil Filter. Start the Engine at Idle and then study the behavior of your Oil Pressure(s) using the in-dwelling Adapter and Oil Pressure Gauge Kit to establish that your Oil Pressure(s) remain nominal. Don’t Race The Engine! Having an assistant will make your life easier while doing this job.

After doing these procedures… if everything goes well, remove the Oil Pressure Gauge Equipment and replace that 16MM to 1/8” NPT Adapter with a Brand New OEM Oil Pressure Sender. Screw it carefully into the Block and do not over-tighten it when doing so.

 

[Mooseman]

If your oil is good and the engine idle stumbles, as mentioned, it's likely a dirty throttle body. Look in the FAQ for a writeup on the procedure.

 

[Steevo]

I have done a flushing procedure on this engine before every oil change for about 4 years, to try to resolve a P0014 code that recurred.
Ya know what resolved it?
The cam position sensor, which I had replaced in 2013.
I put a new one in (under warranty at Oreilly) and the P0014 has not recurred. Bad sensor, I replaced with a new but bad sensor 4 years ago.
New sensor a couple months ago solved that.
So I do not suspect any such problem with this engine, because of how diligent that was all done. And the engine runs OK.
Does the cluster gauges have anything to do with the readings on the DIC? Or is that all coming from the sensor on the engine?
Could there be a cluster problem?
I may check the pressure next to see if it's correct. And put a new sender in for good measure.
Thanks for the help.

 

[Steevo]

I've done that throttle body cleaning before. I may do that after the oil pressure is tested.

 

[Mooseman]

If the idle issue is resolved, it may resolve the oil pressure issue. If the idle is fine and still getting oil pressure messages, the sensor switch may be going. Cheap enough to replace with the parts shotgun.

 

[Steevo]

The sensor is AC Delco 25037205, I think. AKA D1843
The parts interchange on amazon says it doesn't fit, but that's the number Oreilly says fits.
I found that on Amazon for $12. Is that the one?

 

[Matt]

The part number, from what I can find is D1843A. $30.79 on Rockauto plus their ridiculous shipping or $32.65 on Amazon with Prime shipping.

 

[Steevo]

The interchange on ebay seems to call for D1846A. I wonder what the difference is if any?

 

[Mooseman]

D1843A is for the 4.2 so it's a switch
D1846A is for the 5.3 so that one is a sensor for a gauge.

 

[Steevo]

I have a 4.2, and I have a gauge. Hmm. Now I am confused.

 

[Mooseman]

The gauge is fake. Readings are generated by the PCM. The only reading that it real is 0 if there is no oil pressure.

 

[Steevo]

So I need a D1843. OK. I guess I will order one.
$45 at Oreilly, $12 on ebay and Amazon.

If the gauge is fake, why do I have a low oil pressure indication, both by the gauge, and on the DIC.
If the oil pressure is not low, or is not actually measured.
I agree about this being a shotgun thing, and if that is just a switch, I can't see a problem. Hmm. Mind blowing.

 

[Mooseman]

If the gauge is fake, why do I have a low oil pressure indication, both by the gauge, and on the DIC.

That means the pressure switch is not seeing enough oil pressure or it's defective. That's how we can tell if it's just the stepper motor or not. If the gauge is wacked but you're not getting the message, then the pressure is good, but if you get both, either the pressure or the switch is bad.

You might get the message if your idle is so low that the oil pressure is low enough to trigger the switch.

 

[mrrsm]

Just a small H/J ...but On Topic... related to my first post on the matter... This is the Link to my Photobucket regarding the Un-Boxing of this Amazon Deal for the Oil and Transmission Pressure Tester. While I think this thing is DOPE! for the money and what is included inside of the Kit including a Very Long Pressure Hose... It would have been nicer to have Finer Pressure Increments shown on the HUGE Gauge Face... but that problem can easily be solved with a Red Grease Pencil and knowing the Upper and Lower acceptable Oil Pressures being investigated. For under $25.00 ... THIS is pretty Good Deal!. I also scanned all of the Documentation that lists these Oil Pressures for a wide range of vehicles. Please note that the 16MMX1/8" NPT Adapter needed for the LS and 4.2L Engines is NOT part of this Kit:

http://s557.photobucket.com/user/60...RENGINEREPAIR/OILPRESSURETESTER?sort=2&page=1

And... Its still here if you want one...

https://www.amazon.com/8milelake-Engine-Pressure-Tester-Diagnostic/dp/B01N98909D/ref=sr_1_11?s=automotive&ie=UTF8&qid=1515635135&sr=1-11&keywords=oil+pressure+gauge+1/8"+npt+kit

 

[Matt]

So I need a D1843. OK. I guess I will order one.
$45 at Oreilly, $12 on ebay and Amazon.

You need the D1843A. The D1843 is not for our 4.2.

 

[Steevo]

My idle is about 600 after warmup. It can go a little lower but not usually. This indication of low oil pressure seems to accompany a engine stumble. And lower idle. It's stalled a couple of times.
I think the next step since I have no gauge, adapter, or replacement pressure sensor is the throttle body cleaning, which I have done before. So I will look into that today.

 

[Steevo]

You need the D1843A. The D1843 is not for our 4.2.

All I see are labeled D1843. According to Oreilly they have no D1843A.
I also found D1846. That seems to be for the V8. But looks exactly the same. Identical.
Can anyone verify a difference?
I think Mooseman said above that the D1846 is for a gauge, D1843 is a switch, but the parts appear identical.
So i just dunno.

 

[Mooseman]

I'd stay away from the D1846 to be on the safe side. Looking at pics of both, the D1846 definitely has a smaller threaded port so it's definitely for the V8.

The D1843, according to RA, is for vehicles from 1987 to 1999. I'd order the proper D1843A.

 

[Steevo]

I'm really trying, but so many of the listings I see don't use those numbers.
They instead have 250307205. That seems like the most common designation.
Oreilly doesn't know from D1843, D1843A or anything like that.
I guess I will clean the throttle body.

This looks like the part, but it says D1843.
https://www.amazon.com/dp/B000C9N4XO/?tag=gmtnation-20

 

[Mooseman]

https://www.amazon.com/dp/B0016HURFO/?tag=gmtnation-20

 

[Steevo]

That one seems like a two pin plug, but it's hard to see, for sure.
Here's a chinese knock off labeled D1843A
https://www.amazon.com/dp/B077BWV5T2/?tag=gmtnation-20
That definitely has the third pin missing. The one Oreilly said fits had three pins.
I am gonna clean the throttle body. This is just too weird. Hahaha.

 

[Mooseman]

For that, I wouldn't trust CCC (Cheap Chinese Crap). The one I linked only has 2 pins.

 

[Steevo]

Oh, I agree about the CCC. I try to get AC Delco which are usually quite inexpensive on Amazon.
I was out driving today, and I did get the low oil pressure indication, when I came to a stop sign. The engine speed does not necessarily decrease, the tach is indicating 600 RPM when the gauge takes a dive and the low oil pressure flashes on DIC.
No sound of lifters that is normally associated with actual low oil pressure, so I am calling bull$hit on that. I will order the sender.
I wish someone here would say the D1843 and D1843A are the same, I am retired now and saving some money is getting more important than it was when I had good income. The D1843 is about $10-$11. The D1843A is at least $30. Do I sound too cheap?

 

[Mooseman]

Like I said, the D1843 is for much older vehicles. I don't know what's different. Maybe the trigger pressure, maybe the connection, maybe the threads. I wouldn't take the chance.

 

[Steevo]

Do I have to get to it from underneath? I don't see it on the passenger side of the engine from the top. So it must be down below.
Am I going to have to have a special socket?

 

[mrrsm]

Having a proper Oil Pressure Sender Socket will make your life much easier as the outer hex design has rounded corners strictly made so for this Tool:

https://www.amazon.com/dp/B0002SR2RY/?tag=gmtnation-20

As for Access Views… These are some I’ve taken during an Engine Tear Down with the 4.2L Motor mounted on an Engine Stand so it will provide an uncommon view due to the easier access to everything. I can’t say that having long arms would help doing this from the Top Down as I have not had the occasion to perform this R&E on the vehicle. The lower Bracing, Brackets and Covers will make this a problem to reach … but eye balling it from the bottom up with the truck raised on Ramps might offer an easier approach.

If you notice... There is an additional 16MM Port located in line with the Oil Pressure Sender that faces forwards towards the front of the Engine. And while it might be enticing to install the 16MM X NPT Female 1/8" Adapter AND attach the NPT Male 1/8" with the Oil Pressure Tester Hose right there...I would not recommend doing so. The Tester Hose may impinge upwards against the various Serpentine Belt Pulleys and Tensioner and get accidentally get wrapped up in all of that HW when the Engine is Running... so bear that in mind if you decide to perform any OP Testing needed and use the vacant portal when the OEM Oil Pressure Sensor is removed instead.

 

[Sparky]

https://www.amazon.com/dp/B0016HURFO/?tag=gmtnation-20

Get this one. Others may "look" the same but the guts are likely not the same. D1843 is NOT the right part by all interchanges. Likely the pressure threshold is different or something like that.

D1843A is the right one. Don't fart around and try saving money on the wrong part as it will cost you more in the long run. Fix it right the first time.

 

[Mooseman]

I've used a regular deep socket on mine multiple times. Don't remember the size but using the new one, just try it on different sockets. Save yourself the money, especially if you're just gonna use it once, it's not worth it. Heck, I'd even use good ol' Vice-Grips.

 

[mrrsm]

I thought I'd post some images of the GM OEM Oil Pressure Sensor...and the information on the packaging supports what @Mounce and @Mooseman advised about the Delphi Factory making the ACDelco Parts ...Down in Mexico:

 

[Steevo]

So I got the D1843A pressure switch.
Put it in. The old switch seemed to be leaking oil, so it was maybe bad anyway.
I immediately got a "low oil pressure" indication. Unplugged it, and the gauge went up and acted normal. Changed with engine speed, which makes sense as this is a fake gauge anyway.
Normal with the switch unplugged? Huh?
looked at some of the associated wiring, nothing obvious.
Plugged it back in, and acts normal.

This vehicle has had intermittent P0014 codes. Same wiring harness.
This is starting to look like a broken or shorted wire in the wiring harness on the engine.

Cleared the codes, the P0014 has returned. I really don't think that code is real.
What should I look into?
Inspect the wiring harness on the engine. The wires seem brittle from age and heat.

 

[Mooseman]

P0014 could be one of several things. Dirty or malfunctioning CPAS solenoid, bad cam sensor or a bad cam phaser. Check for oil in the CPAS connector, the usual sign of failure. A wiring issue is possible.

 

[Steevo]

With as weird as that acted with the new pressure switch, I am suspecting wiring at the moment.
I have had that P0014 intermittently for all the time I have had the vehicle.
I changed the actuator and the sensor in 2013, and the cam sensor again 2 months ago.
After that the P0014 disappeared for a couple months.
I thought the cam sensor I had installed in 2013 had been defective all that time, but now with the wiring disturbed it's back.
So this is kind of a red flag, wiring issue.
I hear that wiring harness is available separately.
Would anyone know the p/n?

 

[Mooseman]

Someone here just bought one and it cost like $600. You might need to go see a dealer as online microfiches don't show everything.

 

[Sparky]

If it is just part of the harness it may be worth just repairing the part that's bad... maybe. Not sure how much work that would be.

 

[Steevo]

Saturday, the vehicle seemed to run ok except for the P0014 code that was set.
Today Sunday, I notice a random misfire.
I was looking at things and it finally set a P0300. But no MIL.
It has not yet set the cylinder specific code.
I know sometimes with a single cyl problem it may take a while to set the cylinder specific code.
This doesn't at all feel like a bad coil, I know what that's like. But with no MIL, no permanent code yet.
I did notice while looking that the CPAS solenoid can be rotated. I think that is a sign of that thing's broken.
I was originally suspecting the CPAS could be causing the misfire.
Which if wiring problem is shorting it out randomly could cause running problems.
Do you agree that if the solenoid can be rotated that is a defect?

 

[mrrsm]

Re: @Mooseman 's observation about the recent New Harness Purchase by another Member:

https://gmtnation.com/forums/threads/2007-engine-pcm-harness-compatibility.17927/#post-550606

As for the lack of 'permanence' to the setting of the P0014 Trouble Code... This part of the system is subject to the vagaries of variable Oil Pressure that does away with the need for an EGR style of control...and provides a wide band for torque in a surprising manner that allows this unique in-line (6) Cylinder Engine to produce so much Horse Power. However... when the CPAS gets clogged..or its in-dwelling metal screens disappear.... then the Cam Phaser cannot react within its 25 degrees of advance and retard ...and it begins to stumble...especially at idle and looks more like a "Bad Tune Up". While the P0014 is specific to the CPAS... All of the players involved are on this list:

(1) PCM Ring Leader of this Circus
(2) CPAS Uses signals from the PCM to vary the Oil Pressure entering or leaving the Cam Phaser
(3) CPS Senses the ACTUAL position of the Camshaft vs. the VARIABLE position of the Cam Phaser
(4) CKP *** Senses the ACTUAL position of the Crankshaft using Reluctor Notches to locate it while rotating

*** If the Harmonic Balancer Bolt loses its holding power (110 Foot Pounds Plus 180 Degrees of added rotation to meet TTY Specs) then the P0014 may also have a P0016 Code... and much bigger engine problems will happen if that event is not soon solved.

Of all these parts and pieces... the ONLY one that is independent from actual sensor signals in any way is the CPAS ...and so it is the very condition of the Motor Oil....or an Oil Infected Connector...or Missing CPAS Filter Screens that can ruin its reliability. One other very important thing about the "leaking "O" Ring on the CPAS" has to do with a flaw in the method the hole or port that the CPAS fits inside of actually is INCOMPLETELY bored through... it fails by about 1/8" on the very inside of the Engine Head. You might notice that there is a gap between the 10MM Bolt Up Bracket and the outside edge of the Aluminum Head... Well having taken down two of these GM 4.2L LL8 Engines... I noticed that in both cases... as the CPAS Solenoid violently moves the internal pin that routes back and forth to shuttle the Engine Oil into and out of the Cam Phaser... in the same way that a Rocket moves in the direction opposite the escaping rocket nozzle burning fuel... the BODY of the CPAS likewise reacts in moving back and forth causing it to slam against the inner edge of that unfinished machining...and gradually.. that residual incompletely bored soft Aluminum metal begins to Crack and Yield... cracking very slight;y ...but just enough to allow the BODY of the CPAS more freedom to bang back and forth inside of that tube.

The resulting "sliding" causes the Sealing "O"Ring to flatten out and wear down enough to leak out Engine Oil...hence the Failed CPAS problem and the strange Black Streak of Oil all down the Right front Passenger side of the Engine Block. Had the CPAS Tube been completely bored through the head... then the CPAS would be able to completely lay flush...and the 10MM Hold Down Bracket would prevent the CPAS Body from moving even slightly. If you would like to observe just how much force that internal solenoid can generate... just hold the CPAS in your hand and hook up two wires applying 12VDC to it...and Hang On. Here are the images I took as proof of this very problem:

 

[Steevo]

Do you agree that if the solenoid can be rotated that is a defect?

 

[Mooseman]

No. It's just the way it's made unless you're talking about the plastic piece within the metal body. I would change it in that case. If in doubt and with a P0014, I'd just change it. Delphi or ACDelco only. I found the dealer to be the cheapest surprisingly.