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2003 gmc envoy_slt_xl
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11 Posts
Discussion Starter · #1 ·
My oil pressure guage had developed a mind of it's own, mostly staying pegged to 80 psi. After talking to a buddy who is a GM Tech, he said it more than likely was the sensor.

My mission... change the sensor!

The GM Service manual says you have to remove the intake manifold :sadcry:
because this sensor is buried in the back top portion of the engine. I was able to see it from the side and was able to feel it with my hand, so I figured there had to be another way.

All you need to do is...

Disconnect both fuel lines from the intake and remove the PCV hose. This give you all the room you need to remove the electical plug and get a socket on the sensor.

I removed the OEM sensor with a 6 point 1-1/16" socket, swivel, and extension. It fit beautifully and got it right out.

I had to order a replacement sensor from O'reilly ($45). The BWD brand sensor is taller, meaning you need to use a deep well 6 point 1-1/16" socket. The only one I had was an impact socket that has a very thick wall. It wouldn't fit down over the sensor because of the tight area. :bonk:

Sooooo, a trip back to the parts store to get Lisle Tool 13250, Oil Pressure Switch Socket. It is a thin walled deep 1-1/16" socket made for these sensors. You might could get a regular, NON impact deep well socket in there, but the special tool was only a dollar more so I got it.

Got everything tightened up, all hoses/lines re-connected and fired her up. No problems, no leaks, no warning lights.

Life is good (until the next thing breaks). :woot:
 

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2004 chevy trailblazer_ls_ext
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2 Posts
Oil sensor access

I have a 2004 Chev. Trailblazer with the 5.3L. I'm thinking it's the same engine? Did you access the sensor from the divers side? I'm looking at it, and found the sensor. But it looks like I need to remove a lot more than just the fuel line and pvc.
 

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2006 gmc envoy_denali
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Replacing the oil pressure sensor

I have an 06 Envoy Denali with the 5.3L. Engine light came on and my oil pressure sensor was maxed out reading 80. Engine light code pointed to the Oil pressure sensor. Looked it up on these forums, and thanks alisonenvoy, your advice was great and made it a lot easier to change than what others were recommending.

Got the sensor at O'Reilly's for about $36.

"the roadie" posted a diagram, on another forum, of the 5.3L that identifies the oil pressure sensor as part #706. Thanks roadie.
 

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2006 chevy trailblazer_ls_ext
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7 Posts
i have a 2006 trailblazer 5.3 v8 and the sensor is in the same spot. i was trying to get at it today since my gauge is acting up. i couldn't effectively get to it because of the hoses that alisonsenvoy pointed out.

i went to pep boys and picked up a fuel line quick disconnect tool and a oil switch socket so that i can get to it tomorrow. after getting the socket home i tested it on the new sensor and it DOES NOT FIT.

the socket was made by great neck tools and is labeled 1" - 1-1/16". it is just a hair off from fitting and i was thinking about taking a dremel to the socket, but i may just get the lisle socket instead.

note: i has a hard time finding the sensor on the engine.... if you follow the vacuum line back from the master cylinder to where it meets the intake manifold you will see the sensor directly underneath. easiest to reach from drivers side.

ducky
 

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2006 gmc other
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76 Posts
Just happened now

I just started my Envoy and have the same problem freaked me out at first. Turned around and came home, found your thread. Thanks. for advice will attempt to fix now. Is it OK to drive around with it like this as long as I have normal oil level or can it damage something else?
 

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2006 chevy trailblazer_ss_lt
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5,895 Posts
as long as you know your oil pressure really is ok...

I've replaced mine without removing anything, just use a small 1/4" ratchet to break it loose, then a thumbwheel to remove it.
 

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2006 chevy trailblazer_lt_ext
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10 Posts
Would anyone be willing to post some pictures on where to find the oil sending unit on an 06 v8 trailblazer? My guage jumped to 80 today after running normal up until now. It does go to 0 when I shut the truck up so based on the discussions I have seen, I am guessing it is the sending unit. Am I correct?

I would appreciate any help your guys could provide as I have never attempted a repair like this before. Thanks!
 

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2003 gmc envoy_slt_xl
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82 Posts
I have sensor and socket ready but is there a certain precaution to disconnect fuel line from manifold?
 

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2006 gmc envoy_denali
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103 Posts
nelfort, were you able to get the fuel line off safely and get it swapped out. My wife's truck has the oil gauge maxed at 80. Just had the oil changed, since we provided the oil I don't think they put too much in and the dipstick reads correct.
 

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2002 gmc envoy_sle
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4 Posts
as long as you know your oil pressure really is ok...

I've replaced mine without removing anything, just use a small 1/4" ratchet to break it loose, then a thumbwheel to remove it.

For the archives:


I had to spend 10 bucks on a 1-1/16" deep well socket. It is of course a half inch drive. No way were my 1/2" drives going to fit up in that space. I had to weld a 5" piece long of 3/8" round stock perpendicular onto the drive end. Fit right up in there and worked like a charm. Beat the heck out of taking everything off that GM would tell you to take off. Took 20 minutes to get everything ready, then about 2 minutes to swap out the sensor.
 

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2006 gmc envoy_denali_xl
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13 Posts
Easier than I thought (Replace Oil Pressure Sensor)

So needed to replace this part at +110K. Local Pep Boys and Dealer when I called told me as you've heard that the Intake Manifold needs to come out first. Went in there with a flashlight in the Pep Boys parking lot and it didn't look that bad to me. Hell I did the Spark Plugs from the top in just under 3 hours with just removing the Air Filter box and heater hoses, this looked much easier without taking off the Manifold.

Got the part at Pep Boys ($40.99) and socket from Sears since the one Pep Boys had marked for Oil Pressure Sensors wouldn't even fit over the new sensor in my hand. Honestly wish they would make these sensors small enough for a 3/8" drive. While at Sears started looking for some kind of adapter to drop from 1/2" drive to 3/8" drive and ended up finding one called a "Twin Spin Drive Converter 3/8" to 1/2" by Cal-Van Tools (P/N 489). The center extension is 1/2" on one end and 3/8" on the other and slides through for adapting either way.

Prepared for the worse, I started to remove the Brake Power Booster vacuum hose from the back of the Manifold but soon realized the tube it goes on would still be in the way and ended up being able to just sneak under the hose with the socket, adapter and 3/8" drive ratchet. Put a 1/2" drive deep socket with 1/2" drive extension over the 3/8" ratchet handle for leverage and "voila". Honestly it took me longer to compress and slide the Power Booster clamp back up and put the tools away then to R&R the sensor.

Now thinking about it, had I spent the $460 - $520 I was quoted to do this I'd be furious! Question Everything! http://forums.trailvoy.com/images/smilies/suicide.gif
 

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2006 gmc envoy_denali
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22 Posts
Went to a GMC/Cadillac dealer and they quoted me around $500 or whatever for the job, and I was furious. Took my Envoy back to the Chevy dealer I bought it from (about an hr. away) and they replaced the sensor for $100 in an hour.

Seems like places will try to charge you what they can for this part if you dont know what your talking about. Owe my savings to hours of research on this forum!
 

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2006 gmc envoy_denali_xl
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Easier than it looks

Hello I am new to the forums. Everyone on these forums are so helpful and knowledgeable. I have an 06 Denali 5.3 and had to replace my oil pressure sensor because the engine light came on and the gauge was pegged at 80. The sensor is located rear of engine right below the brake booster vacuum line that runs into the intake manifold. I am more of a backyard mechanic, I will try and help with any questions.
 

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2006 gmc envoy_denali
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Piece of cake

After replacing my water pump last week I really dreaded getting into replacing this. I bought the sensor along with the 1 1/16 socket, let it cool down a bit and in about five minutes had the sensor replaced. Really helps to have something to stand on and I used an extension that allowed my ratchet to just slip under the vacuum (?) line right above the sensor; it was maybe 2-3". After the initial loosening jolt it just spun right out.

Love this forum! Has helped tons and saved me lots!

2006 Envoy Denali 5.3
 

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2007 saab 9_7x
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I replaced mine about a month ago, or rather my Brother did. Took him all of 10 minutes beginning to end and that included removing and cleaning the little screen thing under the sensor.

What he said echoes what everyone else has been saying, with the right tools it's a breeze.

Let me say that my Brother is a certified master mechanic for the past 25+ years and has all the tools to make quick work of most things.

The problem I had was with low oil pressure readings after doing an oil change during a timing chain tensioner repair (major PITA). I bought Castrol GTX conventional oil in the correct viscosity and it caused the pressure to drop too low and throw a P0521 code. Since the oil change was less than a month old and only had 7 or 800 miles on it we cleaned the screen under the sensor and cleared the code. it came back 2 weeks later so we changed the sensor. In initial driving after the change the pressure still seemed to run low. So I did another oil change to Pennzoil on a whim and that did it, pressure back to normal. No issue in the last month and a 1/2.
 

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2006 gmc envoy_denali_xl
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41 Posts
When you replace -

This may help your motor last longer. There is a small screen under the oil pressure switch that gets sludge in it and stops oil from reaching your pressure sensor. Pull it out with something like a tooth pick. (I can not seem to find this on engine diagrams) Either clean it, or as I have heard some people suggest to remove it and not replace it. * I AM NOT giving advice) This may have cost me my motor at 110,000 miles. Jasper is aware of this issue and is keeping busy replacing motors due to this and/or the DOD on the 5.3.
 

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2004 olds trailblazer_ls_ext
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2006 gmc envoy_slt
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FrancoP

The oil pressure sensor on a 5.3L GM engine can be removed and replaced easily without removing the intake manifold. The GM warranty time to do the job is .3 hr. the out of warranty time is 3.3 hrs. try and figure that one out.
You can access the sensor from the drivers side of the engine compartment, it's just behind the intake manifold, standing straight up. Advance Auto sells the custom made socket for the job or just use a 1 1/16 deep socket, should be 3/8 drive and 6 point, for the tight clearance in there. You can find a video on U-Tube of a guy doing the job on a Chevy Pick-Up with a 5.3L engine. I changed mine in less than a half hour, just be careful you don't break the connector, thay get brittle as they age.
 

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2006 gmc envoy_denali
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Felt I should reply quickly as everyone has been so helpful on here with my issues.

I had this replaced I believe at Pepboys (cant completely remember)... they did NOT charge to take apart the intake manifold.

I went to the dealer (a very reputable GMC in the area) and they hosed me with the quote saying the manifold had to be taken apart. That is a load of BS as it clearly did not - I believe I had the pressure sensor replaced for just shy of $200 and an hour or so of labor.
 

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2007 chevy trailblazer_lt
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57 Posts
Thank you for this forum. I just had the pressure sensor fail on our 5.3 liter TB 2007. No engine knocking or anything, but OP went to zero and set code PO523. Shop manual did say to remove the intake M. I ordered the part and the special socket and did change without removing the intake manifold. It is tight but not too bad.:thx
 
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