Hi Scotty, I have a 2008 GMC Sierra Denali 6.2L AWD, roughly 245,000 miles. Check engine light came on recently and the code read 0521...oil pressure sensor. Took my truck to get it checked out they ended up changing the front crank seal, valley cover seal (I believe that's what it's called), and the oil pressure sensor. Still didnt fix the oil pressure problem though. Took it back to get a new oil pump put on, still didnt fix the problem. My oil pressure meter is normal when the truck is cool but once it warms up and I start driving it pretty much drops around 10 psi. The engine light is also still on and is an orange yellow color. Any idea what could be causing this problem?? I'm running out of dollars and patience with it but I really don't wanna get rid of it. Please help!!
Put a mechanical pressure gauge on it and verify the pressure.
The wires from the sensor to the PCM might be damaged.
You might want to hook up a mechanical oil pressure gauge as a test to verify the actual pressure. I think on some of those GM engines there is a filter screen under the pressure sensor that can clog up and cause a false low reading.
Could be something as simple as a worn out engine.
