DIAGNOSING ENVOY/TRAILBLAZER LOW OIL PRESSURE (GM 4.2L) 

Great videos on cleaning the oil pick tube! I can tell that was huge project for you.I bot a 05 Trailblazer EXT (192k miles) which had same problem. I drive it for 20-30 mins, then at stoplight, I get the low oil pressure warning and "shut off the engine" message on console.This seems like a common problem for the 4.2l motor over 150k miles. I think Root Cause in most of these is Sludge buildup. Here are the things I've tried before I was finally able to fix the problem without taking car apart like you did:1) Added Seafoam. Problem persisted after driving 100 mi. Did not risk it. Moved to next step.2) Changed Oil & Filter to synthetic, and I added Rislone Oil Treatment. I wanted to clean the sludge (if any) slowly. I figured if that doesn't work, I'll do an Engine flush.3) Replaced Oil pressure sensor (I suspected this wasn't the cause, but did it anyway). I spent more and put on an AC Delco part at $65.I still had the problem for the 1st 100 or so mile, but not as often. It would seem the Rislone & Syn oil was doing a good job dissolving the sludge from oil pick up tube and other parts.The new oil pressure switch made no difference, but investment was worth it.4) Replaced the Variable Valve Timing (VVT) sensor even tho no codes showed up on car computer. Other RU-vids showed how to change that. I bot cheapest one on Ebay for $13. I was surprised at how dark the old sensor was. There was sludge buildup on the screen!I think Oil pick up tube and VVT sensor are most vulnerable for sludge.I made sure to drive the car steady on highway (not city driving) to let the detergents in oil additive do their work. I didn't want to come to stops. Other additives could have probably did the trick as well.Today was the 1st time I drive the truck without getting this issue.It took little patience, and did tasks from easiest to the more complex. If problem happens again, I'll try an engine flush next. My goal here is to dissolve sludge on oil pickup tube without removing the oil pan which we know is a nightmare.thx

I like the way you got such good video views of oil pressure switch because I know it's in a difficult and not very accessible position ! Thanks for your effort !

Just what I was looking for. Thank you! My oil pressure went to "0" while running fine, and had plenty of oil when I stopped to check it. Restarted, pressure went to 40, and then back to 0 after a minute or so of driving. Looks good now! Thanks!

as an owner of an 05' GMC Envoy SLT and 07' Chevy Trailblazer LT, (both having the 4.2) I'm glad I stumbled upon these. your video on how to change plugs and coils helped the Envoy immensely. she had a bad random misfire.

This is amazing you have it done ✔ very well explained.

Also I replaced on my mother in laws truck the throttle positioning sensor and throttle control valve. I still had problems with it AFTER replacing them ... I stumbled onto a video before I gave up saying to ALWAYS disconnect the battery for 5 or more minutes to rest the computer in the vehicle to adjust itself to the new parts and it worked. I have also since done this on my vehicle when I changed out other sensors.. works every time. Thank you for making note of that also.

Great video! I thought it was going to take someone else to do for me, but now, I’m doing it myself. Thanks

Okay...if you try this procedure and then, IF IT DOESN'T FIX THE ISSUE; consider this; you may very well have a clogged oil pickup screen that is towards the bottom of your oil pan, (especially if you did an "engine flush"...and getting the oil pan off is a MAJOR job to get off to reach and clean the pickup tube. This will eventually choke and kill your engine! SO...you can also try this to (as safely as possible) dissolve the sludge that is clogging the pickup tube. How to Unstop an Oil Pump Pickup Tube Without Taking the Oil Pan Off Chances are very good that if the oil pressure has dropped due to a clogged pickup tube screen, the pump is damaged and should be replaced along with new crankshaft bearings as well. There is a procedure, though, that may help if the damage is not too severe. Step 1 Drain the engine oil into a drain pan and remove the oil filter. Replace the drain plug and pour 1 gallon of Berryman B-12 Chemtool or a similar product into the engine oil fill. Do not crank the engine. Let the product sit in the oil pan for 2 days before draining. Step 2 Drain the solvent out of the oil pan. Replace the drain plug and fill the oil pan with solvent once again. Allow it to sit for 2 additional days and drain the product. Inspect it as it flows out of the oil pan. If it is a dark sludge, the process will need to be repeated. Rub the discharge between two fingers and feel for carbon grit. If there is grit present, it will clog the screen. Repeat the process until there is no sludge or carbon grit in the discharge. Step 3 Drain the flush agent one more time making sure it is free of sludge and carbon. Remove the oil fill cap and let the engine sit overnight with no drain plug or oil cap installed. This will allow the engine to air out. Step 4 Install the oil drain plug, a new oil filter and add engine oil. Disconnect the engine computer fuse, or disable the engine so that it will not start. Crank the engine for 15 to 20 second intervals several times, allowing the starter to cool between each crank. This will prime the oil pump so the engine will not have a dry start. Start the engine and pay close attention to the oil pressure. Listen carefully and make sure there are no engine knocks or rattles. If there is noise, the engine requires further repair.

i always watch his videos they are great and really helps please up the good work

Great job amigo... Check the water pump and the alternator bearingsfor noise using the car antenna as a sound carrier... I have a 2002 Trailblazer with that oil press switch prob..Solved use Mobil 1 5w30 with Lucas Too...More lubricity and lower proper flow temp during start up cold condition the lucas adds enhanced lubrication and less friction... Muy buena solucion...Gracias

Great info. I own a beautiful 2002 Blazer ZR2 with the 4.3 Vortec & 300k miles on her. It'll tick when it gets a quarter of a qrt. low on oil. I deleted my leaky oil cooler lines & gained a lot of pressure. I did change my oil pressure switch/sensor located behind the distributor but, it didn't make a difference. My pressure runs around 20 at idle & 40-45 running. It'll hit 50 on a fresh oil change.

YES OMG YES THIS IS EXACTLY WHAT MY ENVOY OIL PRESSURE GAUGE IS DOING AS I SIT HERE LOOKING UP WHAT WOULD CAUSE IT !!!! Thank you so much for your video. Mine is doing this randomly tho. Not constantly.. I’m going to go ahead and replace the switch now. Thank you.

Thank you very much so helpful for me.

I was given an 03 trailblazer with a blown engine. I put a junkyard engine in it (biggest pain in the butt ever!) a year ago. Last summer it overheated really bad and I think that blew the head gasket and warped the head. Went down hill since then. I've had a dozen of the low oil pressure alarms that I thought was related to the head gasket (it was leaking exhaust into the cooling system) but I figured as long as the engine is spinning the oil pump was pumping oil. Well it's had a rod knock for a couple months now and I'm getting ready to put another engine in it. Now that I see that the low oil pressure is a problem with these engines in going to pull the pan off before I put the engine in and make sure there isn't any sludge and the screen is clean. These are great engines but whoever designed them I'd like to punch in the face!

I just saw the 69 vette in the background, you gotta get that running. I rebuilt one 25 years ago and loved it. it was a factory drag car and had a sticker on the 4 speed shifter showing 11.5:1 compression ( actually had the heads decked and was 12.5:1 and needed race gas and premium mixed ) I had the headers into factory side pipes as well. Don't wear shorts and hit that pipe after running for an hour, I literally still have a burn scar on the inside of my left leg after 25 years. It looks weird as no hair grows there. Nothing better than removing the t-tops, pulling out the back windows, and cruising at night in the summer. No ac and radio was crap. It ran 11.9 @107 with standard Gatorbacks. It pegged the rev limiter shortly after the 1/8 mile as it was built for the 1/8 mile. I could do a burnout starting in 4th if I revved it to 3000-3500 rpm and popped the kevlar clutch that took a ton to push down. I regret selling that car, I got a new 1994 vette instead but that was one hella car.

Great video coverage considering the space you had to work with...

Awesome video we have a 06 GMC Envoy XL

Glad that was your issue... I have one with leaking (from connector) O/P switch,,(replaced)--then VVT solenoid (leaking from electrical connector) ,replaced..... Problem got alot better, but still doing it... :( (for 50 years I have been a Chevy guy, but with this modern JUNK they are peddeling, I'll stick with my 86 S-10 with 1967 full built small block 327 or my early model (01-04)daily driver SAAB cars (9-5 and 9-3---before GM finished them off also with bad decisions).... :( (still gave your video a thumbs up!)

Yep. Just happened at 230,000 miles. This has been such a good truck.

THANK YOU SO MUCH FOR LETTING US SEE YOU WORK ON THAT MY ENVOY OIL PRESSURE LIGHT HAS BEEN ON FOR SOME TIME NOW THIS MIGHT HELP ME THANKS AGAIN

You would need a way to apply pressure to it and check the switch whether it opens or closes to pass current for the pressure light. It probably closes to send signal to the light

Hello Kevin I don't know if you are monitoring your posts these days, however if you are I would like to hear your comments. Firstly a great series of videos and very well done under difficult circumstances. I am still chasing the fix on a 2002 4.2 trailblazer which showed the same issues as you had. Low oil pressure at idle. I replaced the oil pump, front cover, pick up tube and oil pressure switch twice and still have the low oil pressure light coming on after 15/20 minutes of driving. No DTC codes are shown. I have removed the dash check and replaced the stepper motor on the oil pressure gage and cleaned the throttle body, (to improve the idle speed). I thought I had it fixed with the idle speed going up to 620rpm from 550rpm. All this time I have had a master oil gage hooked up to the engine and it has always read a steady 75lb psi on cold start up, 45lb psi on driving around 2000rpm and 18lb psi at hot idle. These are all within GM's recommended specs. I have stuck with the 5w 30 mobile 1 full synthetic oil and a quality Hastings oil filter. The engine runs very well is quite and smooth and good for its 157000 miles. I an beginning to think that I either have a PCM issue or a throttle body issue as when you come down from 2000rpm the rpm fluctuates momentarily to under 500 rpm and then goes back up. It is at this point the low oil pressure warning comes on and the gage drops to zero. The master gage is still at 19lb psi. Has anyone to your knowledge solved this problem and fixed it? Thank you John

Good video keep it up helping the world one person at a time . GOD BLESS YOU AND O'REILLY'S

Hi Kevin.This might sound stupid, but after i went trough al the work of repacing the oil pickup tube. (mine is 2wd). The same oil pressure low message came back. After i got pissed i noticed that this contidion ony occur while i was stupped at a traffic light and the car was idling. I noticed some hesitation on the engine and the rpms started getting low and the the dammed lights came on. But if i stpep on the gas a little the ights when off and the oil pressure gauge came back to normal. I was mad, but then my expert mechanic, THE LORD asked me...:Have you changed your air filter an cleaned your throttle bodry?...The answer was...NO. mY ENVOY IS A 2004 WITH ONLY '65K MILES AND OIL CHANGES HAS BEEN performed reigiously...but...I have never changed the AIR FILTER. So i went to Auto Zone bought the filter and trottle body cleaner, did all may homework and gues what??? VOILá! eVERYTHING IS RUNNING smoothly AND THE ENGINE STAYS RUNNING PERFECTLY IN DRIVE WITH THE EMERGEGY BRAKE APPLIED FOR MORE THAN 10 MINUTES. AND NO LOW OIL PRESSURE STOP ENGINE MESSAGES ANYMORE! Thanls God! I hope I can help someone with the same problem. Thanks for your videos an all your work.

Thank you Sir!

I just did this repair on my 2004 Envoy I6. The 1-1/16th socket... does NOT fit. Either the old sensor I removed or the brand new one. It was to big and slipped. I tried my 1” socket and it was to small. I wound up using channel lock pliers on it. It worked but not much space to work with.

awesome bro fro 🇸🇦

Thanks! I have the exact same problem... 225k miles as well.

it is a pressure switch, put your meter to continuity and the black on 1 pin and the red on the other, it will likely read some ohm number ( likely very low to 0- direct short ), if you used compressed air into the hole at the end ( try 15psi first and go up by 10psi each time ) , the continuity should change likely to above 10ohms or more.( I would imagine more like 1k ohms or greater ) The computer reads an open circuit ( just unplug the connector ) as oil pressure ok, and a short as zero ( or below pass level ) pressure. If you ever get a sensor that dies while driving , just disconnect until you can get it replaced. I just got a Rainier and got the low pressure warning even though everything was fine. I plan on putting in a real oil pressure gauge and disconnecting the factory plug as it decreases power when it thinks oil pressure is low even when it is not.

I have a 2002 Chevy Trailblazer with 312,000 miles on it. Bought it at 105,000 miles. I think that it sounds like an alternator bearing noise. Alternators usually spin 3 to 4 times the crankshaft rpm. Hello from north east Montana. 10 miles from the Canadian border.

Thanks man doing it now appreciate the tips the electric connection scared me

Let me finish watching before I comment lol.

Very helpful as always, thanks dude

It sounds like your battery is getting a little weak maybe? Yeah, I have to replace that oil sensor too on my 2003 Chevy trailblazer with 195k miles. Good stuff. Subscribed

Did u replace the wheel hub. I did mine then 3 months later the check engine came on so its probly the other side needs done

Hello, I Have a question, so I have changed my engine oil and it still says "check gages," , I'm thinking that it will be the oil pressure switch. My question is, do I need to change the engine oil again. I changed the engine oil since a week ago.

Thank u

The oil sensors are faulting out cause of dirty oil. The PVC hose can put moisture back into the oil causing the oil to have white spots in it. And in the winter is when it happens the most. Needs a oil catch can in place of the PVC to stop the problem

I had the same p0014 code on my 05 trailblazer I just replaced the cam position sensor. I need to do the oil sensor

So you don't need to do the oil and filter change before changing the pressure sensor? My 2004 chevy trailblazer has the same problem

le hice lo mismo pero las molestias siguen ¿Qué otra idea me puedes dar ?

I had same problem. Changed oil pressure switch with no fix. Added STP oil treatment and problem went away. Apparently 5W-30 is too thin. You need a thicker oil if you have high mileage in your vehicle.

I hade same problem it was my water pump an idler pulley take off fan belt an try wiggling fan it won't leak water, pump is spring loaded seal.

having the same issue with my 05 trail blazer i bought yesterday oil pressure kept goin down there seems to be a slight knock also my coolant is boiling is that a bad aighn of bad motor

Reasonably informative but I just ate half a pizza and the camera work is making me want to hurl! 🤢 LOL

March 2,2020. I have the same issue with the fluctuating oil pressure needle. Thanks for the video, now I know what I am up against. I replaced bearings due to speed sensors, when I bought my 04 used, last year. All good on that front. Anyone know about vibration through the steering column when at a stop? I had to replace an ignition coil a month ago. Done at a garage,and it was more than I wanted to pay, near,$300.00. Was a Florida vehicle for college student, but it came home to NH, and I grabbed it. I like the Envoys.

I didn't take the wheel off I just jacked up my 03 envoy reached up with the oil socket and 3.8 ths ratchet and it came right off.

Another tip go to your local hardware store by some Teflon tape to put around the threads that will help Sealing as well

Did this fix your issues? I recently bought my son an 07 4.2l with 130k and it today had the low oil pressure, stop engine command.. I changed the oil and filter, happens again.. it does have a small power steering fluid leak which is right above this sensor, and it has a new minor oil leak coming from this same area.. im preying its this oil pressure switch, I definitely need a simple easy fix like this.. great video

does this happen on the 5.3L v8 also

Great video BUT too bad he did not do what I did , I bought it on ebay 6.99 OEM and it took me about 10 min to remove and install .

I have an 02 trailblazer 4.2l and my question is about the 2 wire circuit connector that runs to this oil pressure switch. If I wanted to the wiring at the connector what am I looking for? Like is it a ground and a positive or a ground and control? My wiring is very oily and I want to make sure it's not that before I replace the switch. Thanks.

So the pressure switch is typically shorted or closed, you can use the multimeter to test for continuity. It should read 0 ohms. Once the pressure goes above about 10psi, it opens up. But I think your problem was that the switch was internally damaged and leaked oil. Also those vehicles have issues with front wheen bearings...typical problem.

I have the same car and it's due for an oil change ,should I change the oil before or after I change the switch? Thanx

And if the sensor is already replaced the truck was running great but once again the oil goes to 0 ?

Do you have any idea how close the pickup tube is relative to the oil drain plug?

I did not want to take the engine apart or remove the rack n pinion just to get the oil pan to drop on my 2004 Envoy so I could clean the pickup tube. In this Video or the next one Kevin replaces the engine oil with kerosene and this does not work for him maybe he did not leave it in their long enough. I removed the oil and filter in my envoy. Then put a new filter on and replaced the engine oil with 2 Gal of diesel fuel. I let that sit in the engine for 3 days starting the engine once or twice a day for no more than 10 seconds. The now Black diesel was drained and filter removed next added new filter and New Oil and Oil pressure is better than ever.

Weird. I’m watching this 2 years to the date of the making.

Water pump my trailblazer did the same thing

Yea because my oil light came on but I'm full off my mechanic told me that I didn't have no oil pressure he said that replacing the sensor that could solve it

Yeap after reading up on it my car running rich the whole time due to a dirty air filter does that half to do with anything

That noise is your ac compressor. Mine is doing the same thing

Oil pressure sensor switch

Subscribing!!! Thank you!!!

Did you ever figure out that bearing noise?

It sucks that GM put a fake oil pressure gauge on these vehicles to fool us into believing it has pressure when it doesn't or vise versa.

I like your (Ford) LMAO

OIL PICK UP TUBE IS ALSO A PROB WITH THE 5.3 CHEV ENGINES... QUICK FIX

I'm curious to if the knock went away!?

Hey Kevin I messaged you about a year ago concerning my GMC Envoy. Same issue. Did you try using synthetic oil before replacing oil pick up tube? If so, did it help?

Did it fix the problem?

Hey did your car turn off and say low oil pressure?

Sounds like your water pump is bad, grab the fan to see if it wobbles, I just replaced mine.

I need you to come fix my gmc😂

steering pump

i m sure if someone will go to mechanic he will go to replace the oil pressure pump

Is it necessary to take off the wheel

The noise is the Alternater bearing

to hell with the oil pressure switch lets see that camero

Just being honest at 6:12 of the video ur doing a video of nevermind.

ATTENTION FRIENDS! Is a GM defect on the oil pump pressure relieve valve plunger that gets stucked. They should make a RECALL of all vehicles that have this problem, It is very costly to replace the oil pump for something so small and simple. Envoys, Bravadas, Trailblazers and a lot of other vehicles. There should be a Class Action against GM for this. The problem is that when the valve is defective the computer incorrectly senses Low Pressure. That’s why when you step on the gas, the low pressure message disappears! In other words…is just a momentarily lie from the valve that makes the computer think that It has no oil and your car stalls trying to protect itself. This is how I solve it “momentarily” after I did all this… 1. Changed the oil sensor. 2. Flush the engine with Kerosene 3. Replaced the engine pickup tube. 4. Clean the throttle body (was dirty) After all that I was about to give up and sell my Envoy, but I finally found a video where it was explaining the oil pressure relieve valve defect What I did, was to change my engine oil to 40W and use LUCAS oil treatment And Voila! The engine oil pressure went up and the low pressure message has disappeared. (up to now..knock on wood). I wish you all luck. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Il5F_QfHGV4.html

La bla,zer

If there’s oil in the connector, the switch is bad. No testing required…

When making information videos don't talk so much about unnecessary stuff just get to the point thanks for the info

That's all that was wrong

That noise in front sounds like your Water Pump, (Coolant Pump)

BWD! Broken When Delivered

Smh next video stop running your mouth and get to it we didn’t come here to know about your whether

envoys are garbage i hope you never have to put a power steering pump in yours

Jesus too much bla bla bla man just go straight to the point zzz

Thank you very much so helpful for me.

Let me finish watching before I comment lol.