Low oil pressure signal is beeping in the truck?

2004 GMC SIERRA

240,000 MILES • 6.0L • V8 • 4WD • AUTOMATIC

RH309WV

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6 POSTS
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I have about 20 PSI while driving but drops down to about 2 when idle. I replaced the oil pressure sensor and still does the same thing. Oil is up to level, no knocking of the motor. Everything seems fine except for the pressure reading.

Jun 3, 2023 at 8:44 AM

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STRAILER

AUTOMOTIVE REPAIR CONTRIBUTOR
54,178 POSTS

Yep, this happens when the oil pump pickup gets clogged due to sludge or the oil pump pressure relief springs breaks. How does the inside of the engine look is it sludged up? If so, I would start by removing her oil pan to clean the oil pump pickup which is most common.

This guide can help as well:

https://www.2carpros.com/articles/high-or-low-engine-oil-pressure

Here is how to remove the oil pan in the images below. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.

Images (Click to enlarge)

Jun 3, 2023 at 11:38 AM

RH309WV

MEMBER
6 POSTS

How would I know what the inside of the engine looks like? The oil on the dipstick looks fine.

Jun 3, 2023 at 12:32 PM

STRAILER

AUTOMOTIVE REPAIR CONTRIBUTOR
54,178 POSTS

Sometimes you can remove the oil fill cap and look inside. If the inside is clean then I would suspect the oil pump being bad or an internal oil galley plug has fallen out. The only other thing I can think of is to install a manual gauge to make sure the oil pressure reading is accurate.

Jun 4, 2023 at 9:30 AM