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Oil pressure sensor

HYLE

Full Member
Joined
Dec 20, 2021
Messages
25
Just changed out my oil pressure sensor with out removing the intake, I will never attempt that again. Might have helped oil pressure a few pounds but still seems low to me, my Wife's tahoe holds a good 40psi with almost 200k my avalanche only has 147k with 20psi.
 
Did you change the little filter under the sensor.
 
What year is the truck? What RPM are you seeing 20psi?
What year is the tahoe?

2007+ with AFM introduced a high flow (and lower pressure) oil pump. It's normal to see 22 psi at warm idle.
 
What year is the truck? What RPM are you seeing 20psi?
What year is the tahoe?

2007+ with AFM introduced a high flow (and lower pressure) oil pump. It's normal to see 22 psi at warm idle.
It shows 10 psi at warm idle in gear. 2009
 
It shows 10 psi at warm idle in gear. 2009
That is too low... 20 psi is about the lowest I get on my 2010.

What oil filter are you using? Swap to the ACDelco PF48E as a test.

If you hadn't already changed the oil pressure sending unit and got the same reading, I'd advise a mechanical pressure tester kit, but it's still probably worth verifying. here is an example tester https://www.harborfreight.com/engine-oil-pressure-test-kit-62621.html But change the oil filter first unless you're already using a PF48E.

Any glitter in the oil at last change?

Coincidentally I just changed my oil pressure sending unit because it quit working, you are right that was a pain without removing the intake manifold...
 
Yes 10psi on Guage seems very low, I thought mine was low when started getting readings under 30. I had thoughts mine reads lower than normal as I mis-torqued new head drivers side started leaking oil, I am unsure but possibly readings not accurate enough when air getting in.
I've had some small oil leak since I purchased from a dealership, they dicked around the 4 times I bought it back to them. Was an hour drive from my house so 4times wasn't easy task, I should have insisted on receipts each time as after 30day mark they tried say rear main seal needed changing & I would have to pay half the cost 2,500$.
I should have fought in court but I didn't insist paper receipts to get enough evidence.
I did seal myself fixed that leak, then it was side oil pan, & now it's at head gasket.
But back to pressure I would also try checking Guage in display proper functionality. Might be easier than accessing oil pressure sensor & filter again.
I did get lucky I bought my avalanche with 4inch body lift. Helps tremendously working on it. 4in is huge when trying reach tight areas. Made getting to all transmission bolts easy + I don't need to pull manifold to get to oil pressure sensor. Still had to use pads & plywood to lay on over engine so can somewhat see & work with that sensor.
I'm hoping my pressure readings stay bit higher when I correct all oil leaks, I assume it effects it some too.
Good luck
 
Again, what oil filter are you using? Change to the PF48E, or even better the UPF48R like SNES notes and test again.
Thanks, the UPF48E filter raised the oil pressure up 15psi. It holds 25psi at idle now. Thanks again for the good advice.
 
I'm still doing the complete afm delete, this just bought me a little more time.
Just a heads up the O-Ring isn't part of the AFM delete. It's in the oil pan.

The filter buys you more time but once that O-Ring starts to fail it's going to continue and will eventually degrade to a point where you're at risk of sucking oxygen from the pan and causing catastrophic failure.
 
My wife's 2010 tahoe oil pressure gauge went to zero all at once, I replaced the sending unit/filter no change. Bought a oil pressure test kit it shows 47 psi at idle but the gauge doesn't move. You can turn the key on and all the do their little cycle thing including the oil pressure gauge. Any suggestions?
 
My wife's 2010 tahoe oil pressure gauge went to zero all at once, I replaced the sending unit/filter no change. Bought a oil pressure test kit it shows 47 psi at idle but the gauge doesn't move. You can turn the key on and all the do their little cycle thing including the oil pressure gauge. Any suggestions?
New part could be bad too.. Test the resistance across the terminals, what ohm reading do you get?

But an easier start if you still have the old part on hand, test the old sending unit, if it reads correctly I'd suspect wiring at that point.

I only googled briefly, but found this chart for an oil sending until from Marshall Instruments. It may not correlate to our GM trucks, but it may give you an idea. If you see a short (0 ohms) you know it's failed. If you search more, maybe there is published data for GM units. If you need additional data come back and ask, when I have a few more minutes I can look through the service manual too.

Input/Output range:
  • 0 PSI = 240 ohms
  • 20 PSI = 198 ohms
  • 40 PSI = 156 ohms
  • 60 PSI = 114 ohms
  • 80 PSI = 72 ohms
  • 100 PSI = 30 ohms
 
Thumbrule I always heard in the 60's and 70's
7 psi minimum for each 1000 RPM
To be sure oil pressure I would hook up a mechanical gauge to see what it "really is"
20181006_164015.jpg2000 rpm.jpg
 
Last edited:
Took the new sending unit back out, checked the pins it's a "normally closed" switch everything checked good. Reinstalled everything started the engine and it came up to 45 lbs. You know the old saying " don't look a gift horse in the mouth" thanks everybody.
 
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