AFM access
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Pro
Joined: Jan 2022
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From: NY
AFM access
2020 Z51 HTC . Got a Bank 2 CEL for bad AFM. Removed bottom panels covering exhaust and can see the AFM modules from underneath. Can't get my hand up there and was wondering if I remove the exhaust heat shield can they be reached. Also saw on some post that removing the wheel and part of the inter fender they can be reached. Think I saw a picture bit can't find it now. Would like to fix this without removing the rear bumper cover. I just ordered the Paragon AFM simulators and just want to plug and play. Car has 44K miles when the AFM started getting intermittent. My dealer wants to remove the bumper but has never done it and there isn't anyone within a hundred miles that I could find that has done it. So if anyone has replaced the AFM through the wheel well please let me know how it went. By the way I have stock Mpp exhausts. Thanks
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Good luck getting access to the valves.
Melting Slicks
Joined: Feb 2018
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From: Marietta GA
Borrow or buy a bore hole camera to look around the area, and maybe you will see another way to replace the AFM devices. I will agree about removing the bumper, or for that matter, any outside car parts. Removing the rear bumper seems quite easy from all the Forum posts that I have read, maybe you could find a member of the local Corvette Club that has first hand experience. Good Luck.
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2020 Z51 HTC . Got a Bank 2 CEL for bad AFM. Removed bottom panels covering exhaust and can see the AFM modules from underneath. Can't get my hand up there and was wondering if I remove the exhaust heat shield can they be reached. Also saw on some post that removing the wheel and part of the inter fender they can be reached. Think I saw a picture bit can't find it now. Would like to fix this without removing the rear bumper cover. I just ordered the Paragon AFM simulators and just want to plug and play. Car has 44K miles when the AFM started getting intermittent. My dealer wants to remove the bumper but has never done it and there isn't anyone within a hundred miles that I could find that has done it. So if anyone has replaced the AFM through the wheel well please let me know how it went. By the way I have stock Mpp exhausts. Thanks
By MPP, did you mean NPP exhaust? If so, that has four actuators. Two are for the Cylinder Deactivation Exhaust Flow Control Valves and they close when AFM is active. I think you are referring to those actuators/valves since you called them AFM? The other two are the tailpipe exhaust flow control valves, and they close in accordance with the engine sound setting.
So, when you mentions simulators - I think you mean to simulate the actuators for the pair of AFM exhaust flow control valves. If you do that, those valves will default to open, which wont hurt anything, but supposedly may result in an odd exhaust sound if/when AFM is active.
But, if the problem is with the Cylinder Deactivation Exhaust Flow Control Valves/actuators, it might be resolved with the learn procedure for those valves. What were the codes?
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Melting Slicks
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I'm a rookie C8 owner so take this with w grain of salt. I just looked in my AllData account for my '21. The route to get the valves by the exhaust tips is thru the wheel wells.
The valves that are for the V8-V4 system are just aft of the cats, and the book says the bumper has to come off.
Also, if it is the V8-V4 valves you need to do the entire back: wheel wells, trunk liner, airbox, bumper, undertrays, then the entire system aft of the cats is accessible.
Tom
The valves that are for the V8-V4 system are just aft of the cats, and the book says the bumper has to come off.
Also, if it is the V8-V4 valves you need to do the entire back: wheel wells, trunk liner, airbox, bumper, undertrays, then the entire system aft of the cats is accessible.
Tom
Last edited by tomtom72; Jun 22, 2025 at 10:49 AM. Reason: I'm dumb!