Hey all. 09 SS 5.3L, the AFM has literally just stopped working. It's in 8 cylinders and just staying there no matter what. Happened about a month or so ago and I thought it would start working again, but no luck.

Anything I can check/do about this? I've searched everywhere and haven't been able to find a single other person reporting this issue, which is really confusing me.

Throwing any codes, cel ever come on? Not familiar with the mds in the impala, but I know with the mds system in the 5.7 hemi in dodge's that there is a common issue with deactivation due to solenoid failure. Have an intermittent problem with our durango for that very issue. I can clear the code and it goes back to working properly until it throws the code again and might go for 3 to 4 thousand miles before it has an issue again or might trip it again days later after clearing it.

Thanks for the reply. My CEL is on, and it's throwing a code about oil pressure or something (P0523). I had a local mechanic check it out, and he said it wasn't really anything to worry about and was probably throwing only because the last place I took it to (a Midas) used the wrong oil. So after I got an oil change from him, he said it should clear up over time.

Do you think the CEL and codes are causing the AFM to just stop working completely?

Could be. Not sure how the system on the impala works as far as when the codes are showing. With the hemi mds system in our durango there is a display on the console that shows when it is in fuel saver mode and so long as the dash cel is on it does not go to fuel saver. Eventually if you drive a while and the cel goes off it will go to fuel saver mode like it normally does.

Could try clearing the code and see if it goes back to working.

I'm curious about the oil causing something like this Mango. What were you using (oil weight, etc.) to make this happen?

Hey thanks for asking. From what I can tell, the Impala requires 5W-30, but the mechanic I went to said that the Midas people probably used 10W-40. I don’t know how he knows honestly, but he sure seemed sure.

I’ve tried resetting the CEL a few times since then, but it comes back on about 20 seconds after the next I turn the car on. I’m wondering if this is something that I should be more concerned about now.

The code being thrown is P0523 — cause for alarm you think??

Think that code is for oil pressure sensor. If the wrong oil was used, would think it could be possible that could cause the pressure to not fall into specs that the car is designed to run, which might in turn be triggering it to trip the code. If it were mine, think I would consider changing the oil again being certain the right oil was used.

FWIW, the AFM on GM engines uses oil to engage the lifters which then prevent the intake and exhaust valves from opening, so the cylinder compresses spent exhaust gas over and over again, kind of like a gas spring.

Which stands to reason, if there is an oil pressure sensor fault, the AFM would become disabled. I have heard and read that the wrong viscosity oil can cause this very issue.

If that isn't the issue, I know a few years ago two members here had his AFM stop working all of a sudden, then shortly after started throwing the P0523 code. Took it to a dealer, they swapped out the oil pressure sensor and everything started working again.

Hope this helps!

I'm pretty sure the 5.3 is notorious for oil pressure sensor codes. Maybe not so much in the cars, but at least in the trucks. I believe there is a mesh screen on the bottom on the sensor that can easily get plugged that a lot of people just throw away. Not sure if the car is the same setup but it would be worth looking into. Are you able to monitor the oil pressure? Does it seem low?

Did you find out what the problem was? My 08 5.3 is doing the same thing, throwing the same code. Changed the oil to see if that would help, going to replace the pressure sensor tomorrow. Just curious how your situation turned out.

Be sure to replace that lifter oil screen/strainer as well.

I have an 08SS w the same issues. I had codes for crankshaft/camshaft correlation and oil pressure sensor and I started off replacing crank sensor, still got the code after clearing it then I replaced the camshaft sensor and still got the code after clearing it, then I replaced the oil pressure sensor and filter and I still have the code. What do I do? My neighbor said to get the comp flashed? But I am still stuck in 8cyl mode. Did anyone come up with a way to resolve this issue?

As Hatzie mentions a couple posts back, be sure to replace the screen. It sits below the pressure sending unit. It's a frequent culprit.

Doug

.

Hey Mike and Sara - sorry I never replied to you all - the replies on this forum go to an email I check like once a year.


Anyway, this issue ended up getting cleared after I replaced the Oil Pressure Sensor. After that, just being sure to use 5W-30 every time has kept the car running great.


These days I'm running into misfire and rough idle issues, but after replacing spark plugs I'm pretty sure I'm looking at an O2 sensor issue (thanks to some codes being thrown...)


Hope this helps you all! Cheers!