Quick question for NPP C7
Safety Car
Joined: Jan 2015
Posts: 3,941
Likes: 499
From: Northern Virginia
If you replace the mufflers, and leave the AFM valves in place, then you'll have no problems. The car's electronics don't care if the NPP (behind the muffler) valves are working or not.
But if you replace the exhaust system with one that eliminates the AFM valves, the car will notice that those valves are working and display a Check Engine Light (CEL) code on the dash. The poster you quoted says that leaving the transmission in manual mode will prevent the CEL from coming on, but if you put the transmission in D you will eventually get the CEL.
The CEL won't hurt anything, but if another problem occurs you won't know about it, because the CEL is already on.
The solution, it seems, is to leave the AFM valves connected, even though they don't actually do anything any more. Then you won't have the problem of a CEL.
Last edited by meyerweb; Jan 18, 2016 at 03:44 PM.
