I've had my 2007 Avalanche for just about a week and the check engine light just went on. I took it over to Autozone and got it scanned. Only code is P0521, which is the engine oil pressure sensor. Also, I noticed the oil is pegged always at 80 psi. When I turn the key to "ON", but the engine not running, it goes to 60 psi. I disconnected the connector to the sensor and it read 0 psi, as I expected. I picked up a new sensor from Autozone. Think that'll fix it?

It's almost impossible to get to, though. It's on the very back of the engine, behind some plastic piece. Any idea how to get that plastic piece off? Looks like the top engine cover clicks into it. Oh, the AV has 87k miles. Thanks!

 

Welcome to the forum...

Give this thread a read

https://chevroletforum.com/forum/tah...minutes-58253/

 

Much appreciated. Got an AC Delco replacement and the special sensor socket.... I've pulled the "clip" connector off twice now, just to see if I could. There is absolutely NO room back there! That rear plastic piece is perfectly in the way, and my big *** hand can barely get around the fuel line (I think that's what it is). Ugh.... wish me luck.

BTW, any way I'm missing how to take that plastic cover off the back of the engine? Looks like I might have to detach some lines.... It is circled in red below. Thanks again.

 

Well, got the part replaced today. What a pain! The dental floss trick is absolutely necessary. I dropped the sockets and extensions so many times.... the old part actually fell behind the engine, and I knocked it down with the new part, just by complete accident. My ribs are bruised from laying on radiator, but it's done, hopefully for good. Oil pressure reads at about 50. I deleted the code and all looks good for now. Thanks for the link and the help!

 

Good to hear! thanks for following up on the repair and how it went

 

I have a 07 AV. And i have bad oil sensor. I have had similar experience as you have with exception you finally got it changed out. Is there anything you recommend doing to make it easier? Besides taking it to GM.
I have special socket. How about the ratchet , extension swivel? Any suggestions.
Thanks in advance
Scott Williams

 

I used a normal 3/8" ratchet, and two 3" extensions. I couldn't get a single 6" extension past that plastic piece I pictured. I installed one of the 3" extensions to the socket, and put that over the sensor, then brought in the ratchet with the other 3" extension.

I can't stress this enough; attach dental floss to ever single piece. One to the ratchet, one to the special socket, one to each extension, and one to the new sensor. You WILL drop them, and they are irretrievable otherwise. I laid on top of three pillows, but still had bruised ribs. It's going to take a while but it is do-able. Good luck!

Edit: Oh, also, you'll need something to delete the check engine code. You might be able to get a worker from Autozone to do it. They will scan for free, but I'm not sure if they are "allowed" to delete codes. I picked up . Took 2 seconds to erase the code.

 

I know that this is an old thread, but if your reading today, this info may be helpful. I had a low pressure readings on my 2007 Tahoe LT 5.3Flex throwing every couple of days. Oil level was in the full range. I has just bought the vehicle, used. So, I went out a bought a new oil pressure sending unit and filter. Did not replace it after I saw how much of a pain it would be to do myself. I took the vehicle in to a local repair shop for a bid. $600, way too rich for me. GM says to remove the intake manifold to replace the gauge.

Anyway, I did some more searching on the web and found a blog where the owner fixed his problem (low oil pressure) with an oil change. I tried the same. Had my oil replaced with Mobile 1 full synthetic, 5w30. This is GM spec'd oil weight. Anyway, when I drove off, my oil pressure was 40 and is still running 30 at idle and up to 45 on the freeway. No more check engine lights.