PO521 NOT the Pressure Switch.....at dealer.

mike94silverado · April 7, 2015

So First off I have a great dealer and a very nice tech working on the truck. Sunday the MIL came on. I scanned it myself and got a PO521. the oil pressure gauge didn't appear to be any different. I reset the code to see if it was just a fluke as the truck had sat for 2 weeks without being ran. the light came back on the following day within 10 minutes of startup. I again, reset and called to make an appointment. this morning it set again and I brought it to the dealership with the code stored. the tech diagnosed it as a bad pressure switch. I had the screen below it changed at the same time. I left the dealership and it threw the code again.

So the truck is with them right now, what conditions other than a bad switch could be causing this? I assumed that in trouble shooting the sensor he would have checked the actual oil pressure it appears he did not. he told his manager he "threw a sensor" at it and wanted to know where he should go from there.

I still have one month of powertrain left. the sensor replacement was $317. 2010 truck with 46k....

thanks

Doug_Scott · April 8, 2015

When the code gets set, does it do it while just idling, or does the truck need to be driven to set it? Oil pressure may be fine at idle, but at higher rpm it may drop if for some reason it sucks up some air. Oil level in engine when idling may be higher when compared to the actual level at 3k rpm. If the pickup has a crack in it that is covered at idle, may be exposed at higher rpm and allows air into the oil pump. Can't pump air efficiently with an oil pump.

mike94silverado · April 8, 2015

after driving a few minutes.... hope the tech can figure it out. he seemed very puzzled.

gmtech4 · April 8, 2015

Don't tell them what you think it is , .. Not good

Doug_Scott · April 8, 2015

Rob is right. If you offer a possible cause, human nature being what it is, the tech will try to prove you right, knowing that if still does it, he tried what was suggested. There are some techs that will try to prove you wrong as well. Those techs are the ones that feel they have the ultimate knowledge and no customer can possibly diagnose the issue.

What you must tell the tech though is exactly how you can duplicate the issue. In this case, code doesn't set while idling, truck has to be driving for the code to get set. It may get him thinking beyond defective sensor. Be interested in hearing if you can duplicate this while truck is not moving, and you are holding rpm at 2500 for a few minutes. If it does, include that in the duplication scenario. The tech could then check actual oil pressure using a T fitting (so the sensor would still be in circuit) when light would get set

mike94silverado · April 8, 2015

I didn't tell him to put a sensor in it all I told him was the conditions which the code was triggered, and left the last code in there. Honestly, if I wanted to just throw a sensor at it i would have myself cheaper.I just had a feeling it could be something more and I would rather pay for the expertise in solving the issue as I have tried the cheap route far too many times. I left the truck at the dealer so he could start it up in the morning and drive it the same as I have the last 3 days when I've gotten a code.

Believe me I always try to tell exactly whats going on with it but I don't ever try to tell a tech about doing their job.

gmtech4 · April 8, 2015

I didn't tell him to put a sensor in it all I told him was the conditions which the code was triggered, and left the last code in there. Honestly, if I wanted to just throw a sensor at it i would have myself cheaper.I just had a feeling it could be something more and I would rather pay for the expertise in solving the issue as I have tried the cheap route far too many times. I left the truck at the dealer so he could start it up in the morning and drive it the same as I have the last 3 days when I've gotten a code.

Believe me I always try to tell exactly whats going on with it but I don't ever try to tell a tech about doing their job.

Did the tech follow the code ? I'm not sure how you can find out the answer to that unless it's in his write up on the work order , I'm sure he did or at least hope he did

mike94silverado · April 8, 2015

I talked to him he scanned it and said we needed to replace the pressure switch and screen I gave him the go ahead. It wasn't until later I found out he never actually checked the oil pressure out with a regular gauge.

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gmtech4 · April 8, 2015

Flat rate is a real bitch alright

poopandabear · April 8, 2015

I had this issue, luckily it was right after I bought the truck used. They replaced the sensor, no good. Replaced the oil pump, still no good. There is now a TSB that the oil filter P48E does not work in low temps

mike94silverado · April 10, 2015

I had this issue, luckily it was right after I bought the truck used. They replaced the sensor, no good. Replaced the oil pump, still no good. There is now a TSB that the oil filter P48E does not work in low temps

they did the TSB, it specifies 0 degrees, it hasn't been that. Light came back on, on the way home. Traded truck in on a new one this morning. (not entirely due to this problem) wish I could have had a fix for search purposes though..... thanks anyways.

poopandabear · April 10, 2015

they did the TSB, it specifies 0 degrees, it hasn't been that. Light came back on, on the way home. Traded truck in on a new one this morning. (not entirely due to this problem) wish I could have had a fix for search purposes though..... thanks anyways.

I was told 20 degrees for mine. I have a copy of the bulletin somewhere....

Seems like my truck is running fine now. Hope you're enjoying the new ride. What'd ya get?