Will removing the fuse 15 cause loss of torque?
- Thread starter Barend
- Start date
scm
New member
On the latest models (not sure if this applies to yours) removing F15 fixes the valves in whatever state they are in when the fuse is removed - you have to make sure the valves are open when you remove the fuse. Apparently the new facelift models have different behaviour than the earlier ones, which do leave the valves open when F15 (or F43 if even earlier) is removed.
I pulled fuse 15 in my 2019 P380 this morning and got an amber engine warning light for my troubles. Popped the fuse back and the light stayed on so had the fault code reset at my local indie. Just a heads up for anyone thinking of doing this in a 2019 onwards model. The mod does work, but I do prefer having the active exhaust button to change modes.
I have a MY21 P575. I had started the car and had the active exhaust button pressed and valves open. I pulled fuse 15 had no warning lights, the difference in noise at low revs is night and day, sounds amazing all the time rather than at higher revs. Popped the fuse back in on getting home as it has its first MOT next Friday. Definitely taking the fuse out as soon as it’s home after the MOT, it’s even better than before 
davidls said:I have a MY21 P575. I had started the car and had the active exhaust button pressed and valves open. I pulled fuse 15 had no warning lights, the difference in noise at low revs is night and day, sounds amazing all the time rather than at higher revs. Popped the fuse back in on getting home as it has its first MOT next Friday. Definitely taking the fuse out as soon as it’s home after the MOT, it’s even better than before
Strange that I triggered a fault code. I’ll buy an icarsoft off in the coming weeks and test this again and check the code. The indie said there was definitely an exhaust vacuum error code logged. Plus a few old battery related codes as the car had been standing a few months before I bought it.
Barend
New member
davidls said:I have a MY21 P575. I had started the car and had the active exhaust button pressed and valves open. I pulled fuse 15 had no warning lights, the difference in noise at low revs is night and day, sounds amazing all the time rather than at higher revs. Popped the fuse back in on getting home as it has its first MOT next Friday. Definitely taking the fuse out as soon as it’s home after the MOT, it’s even better than before
I removed fuse 15 in the same order as you, and then turned on the dynamic mode. I heard the sound still changed and seemed to become deeper. Is it the sound coming from the stereo?
Dynamic Dek
New member
I have MY21 P450, you can see the exhaust valves. These are operated electrically, not by vacuum and therefore remain in the current open or closed state when the fuse is pulled.
Normally these are open when the engine is switched off, confirm visually valves are open and pull fuse 15.
Normally these are open when the engine is switched off, confirm visually valves are open and pull fuse 15.
Barend said:davidls said:I have a MY21 P575. I had started the car and had the active exhaust button pressed and valves open. I pulled fuse 15 had no warning lights, the difference in noise at low revs is night and day, sounds amazing all the time rather than at higher revs. Popped the fuse back in on getting home as it has its first MOT next Friday. Definitely taking the fuse out as soon as it’s home after the MOT, it’s even better than before
I removed fuse 15 in the same order as you, and then turned on the dynamic mode. I heard the sound still changed and seemed to become deeper. Is it the sound coming from the stereo?
Hi Barend, that is one thing I didn’t try after pulling the fuse, I wonder how it makes a further difference though if the valves are already open and fixed that way because of lack of power. I will remove it again after it’s MOT on Friday and try both modes and let you know.