23bossman

I just bought my first Vette a 2019 C7 1LT. I bought a Borla X Pipe and Cat Back Exhaust 60548 and 11881. I have a professional shop install it but now I’m getting a check engine light with code P12f0 which is “Cylinder deactivation exhaust flow control valve stuck open bank 1.

Can anyone help me here preferably in laments terms. I am no car expert. How can I get this fixed?

62RPO582

I am taking my '19 to the dealership on Wednesday for the same thing. I had a Billy Boat system installed and drove about 200 miles and got the CEL with codes P12E8 ((Cyl deactivation exhaust flo valve feedback circuit high duty cycle bank 1) and P12EA (cyl. deactivation exhaust flow valve closed position bank 1.) I used my borescope camera and looked into the exhaust and both AFM valves are in the open position, so I don't know what the problem is but I will find out Wednesday (I hope).

zk40

I NEED HELP with this too please. Were you able to figure out the problem?

ErnieN85

Thanks FYREANT,

This process worked exactly as posted with the new HPtuners MPVI2. If you have a windows compatible laptop you can download the VCM suite for free directly from the website. As stated above, you only need to download, modify and burn the C304 CCM and will require 2 universal credits. Tuning with the MPVI2 now uses universal credits and is much more user friendly than the previous version. When you buy the MPVI2 directly from HPtuners, it comes with zero credits. You have to buy them separately. Check it out at their website. You can get the unit with credits from Amazon. Not sure how that works though. I chose to buy directly from the HPtuners website with zero credits.



After downloading the CCM file from my Vette, I modified it as shown above. I wanted to try and burn it with no credits. The VCM suite will tell you how many credits you need and then you can buy them at that point. After purchasing the credits you will have to resync your tuner and then the credits will show up in the VCM suite software. There are plenty of YouTube videos showing this process. Once the credits show up, you are cleared to burn your updated file. That's it.



The MPVI2 costs $299, 2 credits cost $99.98 and it literally takes no more than 30 minutes to download the current tune file, modify it and then burn it. Your laptop needs to be hooked up to the internet or the tuner won't be able to verify registration during the download or upload process. It verifies registration with the hptuners website each time you try these actions. At least that is what I experienced. The Vette side of my garage has great WIFI coverage, but the Camaro side has poor coverage and the software wouldn't download my Camaro tune file until I moved the computer outside of the car.



One word of caution, it takes approximately 5 minutes to download or upload the file and is a very high draw on your car battery. I highly recommend having a battery charger or tender hooked up to your battery during the process.



To answer a few of the questions asked about this, here is what I found:

1. The check engine light is now out.

2. No more clicking when the AFM valve motors try to open/close (I pulled the #32 fuse)

3. ECO, Tour and Sport all work as before.

4. 4 cylinder mode also works as before. I don't notice any difference with the exhaust sound when the car switches between 4 and 8 cylinder modes even though the AFM valve stays open all the time now.

5. The NPP valves continue to change the sound as before.



AFM Delete

To do this you will need:

HP Tuners with VCM Suite UPDATED TO VERSION 3.6 and two additional credits

NOTE: The credits needed for this are IN ADDITION to the credits used to tune the ECM. This means that your C7 will use a grand total of 4 HPT credits, two for your engine tune, and 2 for the FSCM tune!



Taken from the HPT forum:

As of Software version 3.6 you can now tune the FSCM/C304 modules however they do cost additional credits in order to license these modules which you will notice once you attempt to flash them. If you have no plans to tune/modify either of these modules then when you start the read process simply select DO NOT READ on the modules you have no plans to modify, this way the software will not ask you to license them. Keep in mind these modules cannot be read via the bus so a stock file is generated for you(you will see a popup that will state this clearly as well).



•1 credit each for FSCM A-F

•2 credits each for C304(C7 Corvette)



To clarify, I am referring to the valves circled in RED in the below picture. We are NOT talking about the valves circled in Green! The valves circled in RED are the AFM valves and are related to Displacement on Demand / Active Fuel Management for “Eco mode”. They serve no other purpose, which is why the Z06 does not have these valves since it does not have Eco mode.







In order to remove these valves from the exhaust, you will need to be able to stop the computer from thinking there is a problem by turning off the codes it throws. The main reason that we could not do this previously is the codes that are generated to illuminate the check engine light (CEL) when these valves are disconnected is not located in the ECM, but rather the FSCM. The same result happens when pulling fuse #32 under the hood as this also disables the AFM but the computer trips out as it thinks there is a problem. The FSCM module handles these codes which is also known as the C304 module.



For testing this, I pulled fuse #32 from the under hood fuse box and after two engine startup cycles received these 6 codes:







The first code is a master code, and the other 5 are individual codes. P26C8 will not throw unless something else throws first. So what are these codes for? Let’s look in the manual. First the P26C8 code indicates this: “Chassis Control Module Requested MIL Illumination”. Again, like I said this is a master code. When the other 5 codes came up, it triggered P26C8 which is the actual code that turns on the check engine light. What do the other codes mean? Lets look:







As you can see, they ALL relate to “Cylinder Deactivation Exhaust Flow Valves” which are the AFM valves in question.



Cool. So all I need to do is turn off the code for P26C8 then right? Whoa there killer… way wrong answer!!



If you turn off P26C8 from working, then you will not get notified for ANY other alert that the C304 module controls! The correct way to do this is to disable all the “Cylinder Deactivation Exhaust Flow Valve” codes individually and leave the P26C8 code fully enabled! If you do the job right, none of the AFM valve codes will trigger P26C8 and you are good to go!



Ok so how do I fix this already?!?!



As mentioned earlier, you’ll need HP Tuners and the VCM Suite installed on your laptop. It MUST be updated to version 3.6 or later or you will not be able to get to the FSCM module to proceed.



Open the HP Tuners VCM Editor software.



[img]blob:https://www.corvetteforum.com/339a5ac0-65eb-41aa-8611-ee1a19ce1a91[/img]



Make sure you have the HPT module plugged into the OBDII port, turn the ignition on (do not start car though). Go to “Flash” and choose “Read Vehicle”.



[img]blob:https://www.corvetteforum.com/647d48ae-e2f9-4428-b586-687f3e37d785[/img]



You will see a window pop up. First choose “Gather Info”. After it has gathered info you will see a window that looks similar to the below one. Here you can see the E92 ECM which is the main computer and the C304 CCM which is the FSCM module we need to tune. Ensure that the drop down box is set to “Read Entire” for the C304 module and then click the “Read” button.



(NOTE: you do not need to read the ECM module unless you need to change settings related to the ECM tune)



[img]blob:https://www.corvetteforum.com/92dddb9c-90ba-4051-a0a9-706abf70db87[/img]



Once the read is complete, it will bring you into the files it read. Here we need to go to the “System” button (number 1 in photo below), and then click the “DTC’s” tab (number 2 in photo below). Now you’ll need to locate the appropriate codes that we need to disable in the list. The codes numbers are those indicated by number 3 in photo below.







Next you will need to locate the codes we need to turn off. I’ll list them here for easy reference:



DTC P12E3: Cylinder Deactivation Exhaust Flow Valve Control Circuit Open

DTC P12E7: Cylinder Deactivation Exhaust Flow Valve Feedback Circuit Low Duty Cycle (Bank 1)

DTC P12E8: Cylinder Deactivation Exhaust Flow Valve Feedback Circuit High Duty Cycle (Bank 1)

DTC P12E9: Cylinder Deactivation Exhaust Flow Valve Open Position (Bank 1)

DTC P12EA: Cylinder Deactivation Exhaust Flow Valve Closed Position (Bank 1)

DTC P12EB: Cylinder Deactivation Exhaust Flow Valve Feedback Circuit Low Frequency (Bank 1)

DTC P12EC: Cylinder Deactivation Exhaust Flow Valve Feedback Circuit High Frequency (Bank 1)

DTC P12ED: Cylinder Deactivation Exhaust Flow Valve Feedback Circuit Incorrect Frequency (Bank 1)

DTC P12EF: Cylinder Deactivation Exhaust Flow Valve Stuck Closed (Bank 1)

DTC P12F0: Cylinder Deactivation Exhaust Flow Valve Stuck Open (Bank 1)

DTC P12F1: Cylinder Deactivation Exhaust Flow Valve Position Not Learned (Bank 1)

DTC P12F2: Cylinder Deactivation Exhaust Flow Valve Actuator Performance (Bank 1)

DTC P12F4: Cylinder Deactivation Exhaust Flow Valve Feedback Circuit Low Duty Cycle (Bank 2)

DTC P12F5: Cylinder Deactivation Exhaust Flow Valve Feedback Circuit High Duty Cycle (Bank 2)

DTC P12F6: Cylinder Deactivation Exhaust Flow Valve Open Position (Bank 2)

DTC P12F7: Cylinder Deactivation Exhaust Flow Valve Closed Position (Bank 2)

DTC P12F8: Cylinder Deactivation Exhaust Flow Valve Feedback Circuit Low Frequency (Bank 2)

DTC P12F9: Cylinder Deactivation Exhaust Flow Valve Feedback Circuit High Frequency (Bank 2)

DTC P12FA: Cylinder Deactivation Exhaust Flow Valve Feedback Circuit Incorrect Frequency (Bank 2)

DTC P12FC: Cylinder Deactivation Exhaust Flow Valve Stuck Closed (Bank 2)

DTC P12FD: Cylinder Deactivation Exhaust Flow Valve Stuck Open (Bank 2)

DTC P12FE: Cylinder Deactivation Exhaust Flow Valve Position Not Learned (Bank 2)

DTC P12FF: Cylinder Deactivation Exhaust Flow Valve Actuator Performance (Bank 2)



In the below screenshot, you will see how to turn them off. Uncheck the box next to “SES Enabled” for each of these codes and then if you click on the “Error Mode” to the right of the check box for each code you will see it is a drop down box. Here, choose “No Error Reported” for each of these codes.







When you are done with that, its time to write the tune file back to the car. Go to the “Flash” menu pulldown and then go to “Write Vehicle”. You will get presented with a box as shown below:



[img]blob:https://www.corvetteforum.com/bb76b7a5-658d-45bb-bb27-334a8fcecc97[/img]



This box is indicating to you that two additional credits are necessary to tune this new module with HPT as I indicated at the beginning of the thread. Once you click “OK” you will be given another popup asking if you are sure you want to continue which you will need to also hit “OK” again on.



After this the tune file is written to the C304 module and you’re all done! You are now welcome to disconnect fuse #32, or disconnect the AFM valve wiring harness connector, or even change out the exhaust to a different one that does not have the AFM valves in it at all!



Thanks to TSloper for his help with this!



Hope this helps guys!