The oil sending unit got bad
Replacing this was not joke or fun . Took over 1.5 hour to remove the sensor and install new back

Best way I found was to remove engine cover , disconnect the fuel line then use a cell video while try to reach the plug
Be ready to get a few scratch on your hands
The sensor is all the way back and in the middle so reach this point is a nightmare

You are going to need a 1-1/16 deep socket , a few different measures extension. Lot of patience and a mirrow/flashlight or cell

The new(ACDelco D1846A GM Original Equipment Engine Oil Pressure ) comes ready to install
Torque 22 lbs

 

Thanks for all the info you are posting. Maybe add your vehicle year to your signature so we know which one you are working on.

 

I'm trying to replace the oil sending unit (OSU) on a 2007 H2 Hummer 6.0 L vortec engine. From the photos shown in the first post of this thread I'm pretty sure I'm in the right place. Although this is an old thread hopefully I'll have some luck. I have the new OSU and special deep socket for removal. My problem is I'm a big guy and I can't even get my hand back there to remove the electrical connector off of the sensor to even attempt to replace it. Keep in mind on the H2 Hummer the hood lift straight up and stays at a 90° angle when open so you can only work from the sides of the vehicle / engine bay. I've attempted to get back in there with a flashlight but there is the fuel rail in the way, evap lines, electrical wires etc. So Any suggestions from an experience mechanic that has done this before on my particular vehicle? Any input, photos, suggestions would be appreciated. This is truly a nightmare to get done. I need some guidance Thanks in advance 👍🇺🇸💪

 

It is doable but it is a very tight and awkward spot to get at. A lot of mechanics will actually pull the entire intake manifold off just to replace them.... that should tell you something. I'd check youtube for something like Silverado oil pressure sender. Pretty much identical engine and probably will find some more tips on replacing it with the manifold still on. It is right at the back of the intake toward the driver side and points straight up.

 

FYI this is much easier if you get the specific socket made for the sending unit, it's a thin walled socket made just to fit. As MixManSC stated, removing the intake makes it so much easier and while you're at it, it's a good time to replace knock sensors and harness. There is also a screen below the sensor that should come out and or be replaced.\

TH

 

Yeah I tempted it today and I just couldn't do it. I didn't want to have to take the manifold off but I guess I'm going to have to. Or I'll just have my mechanic do it. But thank you both for your input and suggestions. If anyone else has a special method I'd like to know lol

 

pulling the intake is the easiest way to do it and it allows you to take a good look at the knock sensors (pre 08/09).

Neal

 

Currently doing this on my bosses 6.0 03 h2. Here’s the link for the best YouTube video to watch. I know it says for GMc but it still applies just minus the workable area. Watch that. You’ll see looking at the drivers side, you can see down into a nook between the intake manifold and the fuel line that curves down behind the motor. There should be a decently thick wiring harness loom there. Look for where the loom splits into seperate harness. Right about the base of the intake/top of the block, one of those pigtails will basically come in right out of the loom and connect to the oil pressure sensor. Just a lil thumb wiggle and the connector comes off. If you have the correct Napa socket, seating the socket is easy. Good luck finding the hole on the way back in! I got lucky, shame I don’t have a girl lol

 

The 03-07 LQ4 is much less difficult to replace then the 08-09 L92 which is nearly impossible as its located at the back of the engine instead of in the intake area.

Couple things that can help, if your working on a low pressure issue once the sensor is out remove the screen under the sensor (LQ4), clean or replace (or just leave it out, not really needed)

Tools that can help make the job easier
3/8 ratchet with extension
1 1/6 oil pressure socket (has rounded corners that fits nicely over the sensor)
torque wrench set to 22ft pounds

One last note take your time and be super careful not to F-Up the connector retaining clip, they are very brittle from age and heat. Have the correct tools and drink heavily before starting, lol

 

That's for the tip I have an 09... When Mine goes....I'll bring it to you......