Fuse 15 Query
- Thread starter Cliffedge
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YorkshireSam
New member
scm said:
Very interesting (and long). I'm not particularly technical but if I've understood correctly and for the benefit of others here, this is the gist in layman's terms...
1. As we know when fuse 15 is removed the exhaust valves don't close, hence the wonderful noise.
2. This is potentially a problem because the particulate filter regeneration cycle only happens when the valves are closed, due to it needing backpressure in the system.
3. The exact consequences of preventing these regen cycles are unclear. The jury is out, with some suggestion (including from a well-know Jag tuning specialist) that this will eventually damage components within the cats, clog the particulate filter and potentially burn out an exhaust gas solenoid. Others dispute this.
4. The regen cycle intervals are very long, so just popping the fuse back in every now and again is unlikely to help.
I read the vast majority of the thread and clearly that's massively simplified, but if I've misconstrued anything feel free to correct/clarify.
A good find, thank you.
Shane_Red_V6S
New member
Agree. Interesting find.
The one thing I haven’t managed to find through all of this is how much it will cost if things go wrong.
I really don’t want to put the fuse in unless I really have to (and will get an aftermarket exhaust as soon as I am close to ending my warranty). However I have no idea how much I am gambling with if I keep it out for the next 10 months (and probably only a couple of k miles)
Does anyone know what a rough idea of the costs if things do fail?
The one thing I haven’t managed to find through all of this is how much it will cost if things go wrong.
I really don’t want to put the fuse in unless I really have to (and will get an aftermarket exhaust as soon as I am close to ending my warranty). However I have no idea how much I am gambling with if I keep it out for the next 10 months (and probably only a couple of k miles)
Does anyone know what a rough idea of the costs if things do fail?
mickjaguar
New member
It's all a bit vague as I've not seen any information on how a regeneration is triggered, nor how often this typically happens or the time involved.
I've had fuse 15 removed for most of the last 4 years and 12k miles. The fuse does get put back before going for its annual service/MOT and around that time it will cover a few hundred miles with it in place each year.
After reading about the potential issue, I have recently installed the 'claws out' module. A lot of my journeys are typically an hour or two, so I'll operate 'claws in' regularly to give it a chance to do any regen. It'll also be nice to have it a bit quieter on some of those motorway journeys for a change.
I've had fuse 15 removed for most of the last 4 years and 12k miles. The fuse does get put back before going for its annual service/MOT and around that time it will cover a few hundred miles with it in place each year.
After reading about the potential issue, I have recently installed the 'claws out' module. A lot of my journeys are typically an hour or two, so I'll operate 'claws in' regularly to give it a chance to do any regen. It'll also be nice to have it a bit quieter on some of those motorway journeys for a change.
JAGBOB
New member
I have read a lot of different threads and Jaguar forums regarding the removal of Fuse 15 and some comments are unsure, and others are sure it will have an implication with it removed. What I have learnt and understand is that the Fuse 15 supplies power to the exhaust valves, but also the ECU takes information from the active fuse 15 and the ECU controls a regeneration valve in the fuel system. The regeneration valve is operated when the ECU has sensed the need for the regen. If the Fuse 15 is removed it does not allow the operation of the exhaust valves and is not operating the the information element in the ECU.
Today I have spoken to Chris at Mod stock of his views and opinions on the Fuse 15 concerns of which he was well aware off and he has also experienced the same issues as Paul Busby at Viezu tuning who raised this as a concern several months ago. Chris did confirm that the failure rate will increase in time as it depends on driving styles, miles etc. He also advised the following options.
1, Don't remove fuse 15 and have no issues.
2, If you remove fuse 15 for some time then refit it again for the same distance travelled with it removed. But thats your 50/50 gamble.
3, Fit a remote plug & play kit. The kit is fitted by unplug the exhaust valve plugs and fit the kit link plug wire and refit the original valve plug to the extra wire plug supplied. Do this on both exhaust valves. You have the Fuse 15 fitted as normal then you can operate the exhaust vales from inside the car buy a remote on/off fob. Also with having Fuse 15 connected the ECU will also operate the regeneration valve.
I have ordered a remote plug & play kit today to try out. When I have it fitted I will report my findings.
Today I have spoken to Chris at Mod stock of his views and opinions on the Fuse 15 concerns of which he was well aware off and he has also experienced the same issues as Paul Busby at Viezu tuning who raised this as a concern several months ago. Chris did confirm that the failure rate will increase in time as it depends on driving styles, miles etc. He also advised the following options.
1, Don't remove fuse 15 and have no issues.
2, If you remove fuse 15 for some time then refit it again for the same distance travelled with it removed. But thats your 50/50 gamble.
3, Fit a remote plug & play kit. The kit is fitted by unplug the exhaust valve plugs and fit the kit link plug wire and refit the original valve plug to the extra wire plug supplied. Do this on both exhaust valves. You have the Fuse 15 fitted as normal then you can operate the exhaust vales from inside the car buy a remote on/off fob. Also with having Fuse 15 connected the ECU will also operate the regeneration valve.
I have ordered a remote plug & play kit today to try out. When I have it fitted I will report my findings.
JAGBOB said:
Look forward to hearing how it goes.
But would option 3 not still reply on your running the car with the valves closed, it's just much easier to do so with a remote?
On my Supra, I disconnected the connector from the rear silencer and connected it to a dummy module which tricked the car into thinking it was connected to the valves and controlling them. Part was £20. Surely this is all that's required.
JAGBOB said:
Very interesting, how much is their unit? The one I quoted from ASR sounds good but is over €300.
Also, did they say if the regen will still occur if their unit has the valves open?
My understanding (from reading the forums) is the ECU is looking for confirmation that the valve is closed, rather than just fuse 15 being in. The US forum says, if I remember correctly, the ASR unit does tell the ecu the valve is closed, and so the regeneration does happen
scm
New member
One thing not noted is that, AIUI, on later cars when you remove the fuse the valves stay where they are - so if they're shut when you pull the fuse they stay shut. I'm fortunate in having an early car so not affected by that, and I'm too lazy to take the fuse out anyway - I like mine just the way it is.
YorkshireSam
New member
So let's say you fit a remote-controlled fuse bypass as some members have done, so the exhaust valves can be fully opened and closed remotely... https://www.ftypeforums.co.uk/viewtopic.php?t=8890
Would the ECU think fuse 15 was in situ until the switch is activated? Or would it think the fuse has been permanently removed?
... Or is the jury still out on that?
I think this is a slightly different procedure to the exhaust valve bypass suggested by ModStock in one of the comments above?
Would the ECU think fuse 15 was in situ until the switch is activated? Or would it think the fuse has been permanently removed?
... Or is the jury still out on that?
I think this is a slightly different procedure to the exhaust valve bypass suggested by ModStock in one of the comments above?
mickjaguar
New member
f
The 'claws out' remote module is basically putting a switch across the fuse terminals that breaks/makes the circuit. The same as removing/replacing the fuse.
In simple terms the 12V flowing through fuse 15 is the +ve feed cable to the valve soleniods and anything else powered on that circuit (the -ve 12v side will be those individual components earth connections back through the bodywork). When fuse 15 is removed the +ve feed going along that cable/circuit is severed.
The 'claws out' remote module is basically wired in a loop across the fuse 15 terminals, so the 12V +ve feed flows around this extra piece, rather than just in and out of the 5A mini fuse. An inline fuse is put in this loop to replace the 5A circuit fuse no longer plugged into fusebox. The remote module/relay installed within the loop, is basically a switch that breaks the +ve circuit etc.
YorkshireSam said:
The 'claws out' remote module is basically putting a switch across the fuse terminals that breaks/makes the circuit. The same as removing/replacing the fuse.
In simple terms the 12V flowing through fuse 15 is the +ve feed cable to the valve soleniods and anything else powered on that circuit (the -ve 12v side will be those individual components earth connections back through the bodywork). When fuse 15 is removed the +ve feed going along that cable/circuit is severed.
The 'claws out' remote module is basically wired in a loop across the fuse 15 terminals, so the 12V +ve feed flows around this extra piece, rather than just in and out of the 5A mini fuse. An inline fuse is put in this loop to replace the 5A circuit fuse no longer plugged into fusebox. The remote module/relay installed within the loop, is basically a switch that breaks the +ve circuit etc.
Is this all a red herring? If you take a look up the four pipes you'll see that each of the two outermost pipes have a butterfly you can easily see. When the engine is off, it's wide open, presumably to ventilate the rear box. When you start the engine, it closes instantly. If you hit the exhaust button it immediately opens again and stays open. Why would pulling that fuse do any different? It's not as if there's a second stage exhaust flap for even more noise.
I totally get the arguments for leaving it alone so as not to interfere with the particulate filter regen process. You're really going to be in trouble if that filter gets so clogged it blocks the exhaust, strangles performance and makes it even quieter. I also have an XFS 3d and can tell when a regen of the dpf starts in that. So far I have been unable to see this regen happen on my P450 despite covering 1000 miles now. I have an Autel P200 that shows details for the dpf in the XF, percentage full, miles since operation etc. but for the P450 the software doesnt seem up to date for GPF equipped F Types.
I totally get the arguments for leaving it alone so as not to interfere with the particulate filter regen process. You're really going to be in trouble if that filter gets so clogged it blocks the exhaust, strangles performance and makes it even quieter. I also have an XFS 3d and can tell when a regen of the dpf starts in that. So far I have been unable to see this regen happen on my P450 despite covering 1000 miles now. I have an Autel P200 that shows details for the dpf in the XF, percentage full, miles since operation etc. but for the P450 the software doesnt seem up to date for GPF equipped F Types.
mickjaguar
New member
Willieo said:
This had all owners baffled to begin with and again it was the guys in the US that figured it out. It's a bit sneaky, in that as soon as you increase the revs, ususally by driving off, the ECU will shut the valves partially or fully depending on the setting. However, the valves are full opened in two scenarios to relieve any back pressure, when over 3500rpm or when under full accelaration. A group of us experimented using one of our cars at SImply Jaguar Beaulieu a couple of years ago (the marshalls weren't too pleased) and we could see the partial closing going on.
From what I've read, petrol particulate filters differ from diesel in some aspects of operation. There is significantly less soot (something like 30 times less) hence the filters are much smaller and often can be placed nearer to the manifolds. Petrol engines/exhausts run much hotter than diesel and can naturally regenerate during normal hot running, whereas a diesel needs the exhaust gas temperature artificially increased to do anything. The regen on petrol appears to be when the exhaust gets hot and particularly on overrun when there's more air than burnt fuel going through. It seems to happen fairly quickly too, under the right conditions. Cars which do a lot of short journeys will probably have more soot as they will run rich when cold and probably not get exhaust temperatures high/often enough to burn the soot, in which case my guess is that the ECU will run the mixture lean to raise temps and trigger regen. Whilst diesels require contant speed driving to regenerate, it seems that petrols might benefit from a different approach adopting high revs and then lifting off.
Just my thoughts, as I'm not and engineer. Here's an interesting video, showing a petrol ingenium engine with a blocked filter. This is perhaps most relevant to the P300's as it's the same engine derivative (we know that pulling fuse 15 on these can throw limp mode) but I'd imagine the basic principles are the same. Taking it out for an old 'italian tune up' seems to be as valid today as it was in days gone by!
https://youtu.be/KyUb8Hp_YT4?si=4druyoWpivad2mQf
JAGBOB
New member
I got the ASR RX1 plug & play kit today and was easy fitting buy routing the wires above the exhaust heat shield and fixing the small control box behind the RHS of the wheel arch liner. Cabled tied the wires to the frame below the rear diff unit.JAGBOB said:
The remote key fobs have three positions and can be operated from inside the car when driving. Went for a drive and found the following experience with the fuse 15 fitted standard.
when no 1 is pressed and the car is in sport, dynamic and normal mode the remote exhaust valves are always open giving you all the noise, pops and bangs which is the same as having fuse 15 removed.
when no 2 is pressed it allows you to drive the car the same as if fuse 15 is fitted. the exhaust valves are operated on/off automatically.
when no 3 is pressed it closes the exhaust valves constantly even if you use sport, dynamic or normal mode and the exhaust is very quite at all times.
So hopefully with having the kit fitted this will allow the regen to operate when required when no 2 pressed and also give the same constant louder noise when no 1 is pressed.
Thanks for the follow up Jagbob.
Am I correct to assume you can also change the setting whilst driving? It is a bit annoying that with the claws out approach you have to follow the right sequence when starting the engine (on the newer cars) for it to work.
I don't see it on mod-stocks website, is that where you got it?
Am I correct to assume you can also change the setting whilst driving? It is a bit annoying that with the claws out approach you have to follow the right sequence when starting the engine (on the newer cars) for it to work.
I don't see it on mod-stocks website, is that where you got it?
scm
New member
The "standard" valve opening strategy also depends on the MY and software levels, so it's pretty much impossible to definitively state exactly what happens with the valves and cover all scenarios. in my MY18 it oroginally opened the valvse fully both in dynamic mode and also when I operated the actve exhaust switch. After a software update the dynamic mode behaviour was unchanged (apart from setting all my confurable dynamics to "comfort") but when I operate the switch the valves don't open until about 1500 prm.
Magnus_Nara
New member
I have a 2020 P450 (facelift) I took fuse 15 (5amp fuse) out and it makes a world of difference. However, I am told that this fuse is also responsible for the exhaust gases recirculation sensor, apparently I needs the valve closed to run its clean, something along those lines. I got a check engine light and was told I should put it back in as it could case damage top the engine/cause the sensor to fail.
If you are UK based, I am taking my car to mod stock who modify the back box. I am told this will significantly improve the volume at lower RPM.
What I can't quite figure out is this, my car has the exhaust button, press it and it appears the valve stays open. However, it still sounds like a valve opens at 3.5k rpm and that's when you get the pops and crackles. When you remove fuse 15 it pops and crackles from about 1.8k rpm.
Is there second valve closer to the engine? Is this EGR Vavle what's causing the restriction in sound? I can get a remote valve for the exhaust but if the problem is a valve further up the system, I'm not really sure is going to cure things.
This could just be a waste of £750 but I'll do it for the greater good and get back to anyone that's interested. Getting the exhaust mod on the 16th of October (2025 for anyone just, ping on in the future)
If you are UK based, I am taking my car to mod stock who modify the back box. I am told this will significantly improve the volume at lower RPM.
What I can't quite figure out is this, my car has the exhaust button, press it and it appears the valve stays open. However, it still sounds like a valve opens at 3.5k rpm and that's when you get the pops and crackles. When you remove fuse 15 it pops and crackles from about 1.8k rpm.
Is there second valve closer to the engine? Is this EGR Vavle what's causing the restriction in sound? I can get a remote valve for the exhaust but if the problem is a valve further up the system, I'm not really sure is going to cure things.
This could just be a waste of £750 but I'll do it for the greater good and get back to anyone that's interested. Getting the exhaust mod on the 16th of October (2025 for anyone just, ping on in the future)
JAGBOB
New member
I got the Mod stock rear box done last year and the sound is a lot better than standard. If you read above my fitting of the exhaust remote valves ASR control unit which saves you removing and refitting the fuse 15 and this also allows the exhaust system to regen automatically when required and no more future issues regarding the catalyst system. There is no other EGR valve in the system that causes the sound restriction.Magnus_Nara said:
scm
New member
Magnus_Nara said:
Are you in dynamic mode when you press the exhaust switch? That'll shut the valves. I don't think there's really much point in the switch since if you want valves open, just put it in dynamic, if you want quiet, don't use dynamic.
Of course, the valve behaviour depends on software levels and MY, so it's hard to generalise on how it all behaves.
