08 Tahoe - Oil Pressure Gauge Reading 0 - P0523

[08TahoeVibes]

Good Evening Guys,

This forum was of a great help and a wealth of knowledge when I was chasing a vibration a few weeks ago so I am returning again with another issue to gather your thoughts on.

Vehicle - 08 Tahoe with the 5.3L Flex (162k Miles)

I went to leave for dinner this evening and I noticed while pulling out of the garage the oil pressure gauge pegged at max, 80. I continued to pull it out and then decided to check the oil level while leaving the vehicle running. The oil level on the dipstick looked good and when I got back into the driver's seat the gauge was now reading 0.

A few moments later, the check engine light came on. I scanned for codes and was returned with P0523 - Engine Oil Pressure Sensor/Switch "A" High.

I went ahead and pulled back into the garage which is where it sits at currently.

I don't have a dealership that I trust to take it in for service and we are not against replacing the oil pressure switch on our own IF it's going to be remotely possible and without taking off the entire manifold. We watched some Youtube videos on others doing this and checking the screen under the sensor so we have a general idea on what needs to be done. Naturally, the switch is all the way on the back of the block tight against the firewall which seems like a ton of fun to get to.

Before we go down this road, looking to gather opinions and any tips/tricks anyone might have that has done this before.

Does it make logical sense to start with this sensor? Is there anything else that you might suggest checking first before jumping to this conclusion? Any explanation on why the gauge went from 80 to 0 in a matter of a few minutes?

Vehicle has had routine maintenance and oil changes as needed and has been far from neglected.

Appreciate any and all input in advance!

 

[j91z28d1]

sensors seem to be able to fail high or low. mine failed high the first time too.

most likely the sensor. in general it's recommended to replace with oem, either local dealer. something like gm parts direct or rock auto. but even those fail sometimes but less often than the cheap ones or the counterfeit ones in Amazon that look oem.


you can pull the intake, it's honestly not as hard as it looks. Just need some patience, but it can also be done without it. Just need a good socket that fits it, and with some extensions it's doable.

a top side creeper goes a long way to helping when working under the hood of these tall vehicles. I believe they can be found for around 100$. it you can find a place to store it, to me it's a back saver if you plan to do repairs yourself.

definitely change the filter under the sensor. it's a good time to see how dirty or is too. Will give you an idea of how gunked up your engine is inside too. but I don't think a clogged filter is what you have because it maxed out for a bit.

 

[j91z28d1]

I didn't buy one since I have a pretty good amount of tools, but I have this part number saved as the socket for the sensor. if you pull the intake, you probably dont need it. but if you go in from the top, you definitely need a socket that fits.

j41712

 

[08TahoeVibes]

Awesome, thanks for sharing. You’ve always been an awesome contributor here so thank you once again for your time!

I have (what I believe to be) a similar socket, ACDelco Engine Oil Pressure Sensor (12677836), and the accompanying filter (12585328) coming this week.

 

[08TahoeVibes]

Closing the loop here.

We went ahead and replaced the sensor this morning and can confirm that the pressure gauge has returned to life. We ended up not doing the filter that sits below inside of the block as we ended up not removing anything other than the engine cover and you really are doing everything by feel at that point.

Total job took us about 2.5-3 hours with frequent water/body breaks.

A few things to note for the next person that might tackle this on their own:

- We had better luck using a straight 6" extension on the socket and grabbing the smallest head ratchet that we had eliminating any swivel sockets all together. Best access is from the front of the vehicle, putting your weight onto the alternator, and resting your head against the cowl for support. It's uncomfortable, it's tight, but it's doable.
- We had some issue getting the socket separated from the oil sensor and ended up just pulling the two out together. We started with running some fishing line inside of the socket for fear of dropping it down into the engine bay - this didn't work and was not allowing the socket to drop entirely down onto the head of the sensor so we abandoned this idea pretty early on.
- The part number from the oil sensor was #12616646 and we replaced with GM Genuine Parts #12677836.
- The new sensor did not include the yellow O-Ring and grey piece inside of the connector. Use a pick to remove from the old part and move to the new. The pick was also useful in getting the connector disconnected from the old sensor. Mark your socket in reference to the clip on the sensor as it will be covered up as you are tightening down with the socket.



- First startup after replacing, the pressure gauge was still reporting 0. By the time, I was scanning for codes it started to react and settled right around 40. I cleared the code and the CEL cleared.

More mechanically inclined people might consider removing the fuel lines as these seem to mostly be in the way the entire time.

Thanks again for the input!

 

[West 1]

So I see the sensor is replaced, is your oil pressure back to normal? Nice work.

 

[08TahoeVibes]

Yup, back to normal operation now. Increases as expected when in neutral and bringing the RPMs up.

Apologies if that wasn’t clear.

 

[Fless]

I hope it stays good for you, but I'm afraid that you may regret not replacing the screen as noted by @j91z28d1. They can get clogged and mess with your pressure indications.

 

[08TahoeVibes]

Agreed and was weighing the options as the opportunities showed themselves.

We appear to be getting valid readings for now. If it acts up again in the future, then we can have some reasonable assurance that it’s not the sensor itself, and have the screen/filter already to replace.