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Restricted performance


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Good evening everyone.

My names Matt and I am new to the forum with this being my first post. sorry this is going to be a long read.

I recently bought a XF 3.0d S with 125k on the clock and with a "restricted performance" issue that I was hoping to fix. I got it cheap because of the restriction and couldn't pass up the offer.

I am a mechanic by trade so know my way around some makes and models mostly year 2000's and prior and not to up to scratch with modern cars.


So a little about the car, the chap who had it before me had the warning come so he took it to a dealer who diagnosed it as a turbo needing replacing. They carried out a smoke test and found it leaking from the turbo housing also found a P1247-00 low boost pressure DTC.


He then took it to a independent garage who diagnosed it with a clip missing from the intake pipe to compressor housing (miss diagnosed leak test from jaguar) they refitted it correctly and carried out a vacuum test. They found that a pressure control solenoid was faulty so replaced it. This did not fix the fault. They also found a split pipe from the vacuum test so replaced that which still did not fix the fault.


He then took it to a 2nd independent garage who found a DTC for low boost pressure, engine Oil temp sensor circuit, ride height sensor F/R, Air flow sensor fault. They replaced one Air Flow Sensor and put a turbo on from the recommendation from Jaguar, again this did not fix the fault.


He then took it to a 3rd intendant garage who found only the P1247-00 low boost pressure DTC, They checked the wiring and vacuum operation which came back ok. They then removed the exhaust and took it for a road test to which no faults were thrown. There recommendation is to clean the exhaust system.


He then took it to a 4th garage who specialised in cleaning DPF's. They took it off cleaned it, re-fitted it and this cleared the codes and the car drove perfectly.


He then had the car on his drive way after getting a work van and only used the jag every now and then. With no substantial long journey. after 2-3 months the restricted mode came back, to which he then sold it to myself.


I have had the car a little over a week now and found that the only fault code to be the P1247-00 low boost pressure, I also noticed the "service due" notification. Work I have carried out is so far, changed the recirculation valve with new OEM part. the old one looked ok no rust but heard this is a point of failure, whilst that was off I renewed all jubilee clips on all boost pipes, I replaced the o-rings on any part I could see Oil leakage around its general area, on the throttle body housing and the elbow connecting to this. Changed the fuel filter and air filter with OEM parts. I have yet to carry out an Oil change. I have visually inspected the intercooler to which I cant see any cracks or the orange gasket sticking out, I have also visually inspected the manifolds to which I cant see any cracks (no oil marks around the manifolds or intercooler) I still have the P1247-00 code and restricted performance mode. I have bought a leak tester to try next also to look for any boost leaks, but previous test came back ok. I also have an Autel 808pro that can carry out a forced DPF regen.


Now my question is can these cars put it into this mode if it knows it needs and oil change. Also which I find strange is that previously it didn't throw any faults or have any DPF warnings on the dash or stored on the ECU when they carried out the clean previously which fixed it before. Can the DPF block on these enough to cause restricted performance without throwing any DTC's?


Sorry for the long read, I am kind of pulling my hair out with this one.

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usually once the dpf's get blocked cleaning them is only a short term fix

I'd try getting it cleaned again and see if the fault clears,

diesels now dont like shorts trips and dont like standing, they block up if there not run and run up to temp correct, wont get the dpf's hot enough and clear the soot out

once clear they need regular long runs  for them to keep the dpfs clear, some people use additives, they help the exhaust gasses get hotter and burn the soot out of the dpf's

this is why a lot of people remove the dpfs and have them mapped out, blocked dpfs can cause diesel to accumulate in the engine Oil and this eventually destroys the crankshaft

keep and eye on Oil, if Oil level goes up, needs regular oil changes

the actuators on the turbos are electronic, if they soot up they can go stiff and also cause similar problems



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Thanks for the reply Joe.

To my understanding the ECU should pick up and throw a DTC + warning light when the DPF's need a clean! or is this not always the case with XF's?

I am planning on taking the DPF off to get it cleaned professionally, but also don't want to be doing this regularly if they then block up in less time.

Also would the turbo actuators, if they are going stiff, would this cause a fault code? or do they need to stop operating altogether to throw a code?

Lastly having the DPF's removed, I know legally they would fail mot from just being removed. But mapped out would this cause the vehicle to fail emissions test?

I will be doing a full Oil change this week as the "needs service" warning has come up so will check the consistency for fuel.

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yes all the al the faults should give codes, but not always

once its cleared and its allowed to run properly and regens correct the dpfs should stay clear

legally they should not be removed, bu a lot of people do, removing the guts on the dpfs throw up faults, having it mapped out removes warning lights so it all works correct, they still pass mots correct



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Once I have done the Oil change I will get the DPF cleaned for sure and see how that plays out. Like I said before the only fault code I have being thrown is the P1247-00.

I will be doing a mixture of around town driving and a couple times a month doing a 300 mile round trip.

I can force regen the DPF's using my ODB diagnostic tool, On that case would force regening the DPF's a couple of times a month hurt the DPF at all?

Sorry for all the questions.

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I am a XF 2010 3.0 owner and am completely non technical. I have become very sceptical about Jaguar fault messages. I regularly get GEAR BOX FAULT, DSC NOT AVAILABLE, PARK BRAKE FAULT and recently, WATER IN FUEL. The car drives perfectly and these faults all disappear and reappear in concert.

I did have a power loss problem some months ago which was diagnosed as the GAS REGENERATION VALVES, which a Jaguar agent quoted £1100/1200 for. I got a mate to blast them with ceramic dust (cost £150) and it has run perfectly since - apart from the b****y fault messages.


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Thanks for the reply bill.

I work on trucks mainly at work, what I have noticed with the modern ones is when the batteries fall below a certain point they do what we call "christmas tree" and throw faults left right and centre. they are 24v systems and drops down to 22 can cause it, they still have enough juice to start the vehicles up. I'm assuming modern cars will probably do the same with voltage drops having them running on can-bus wiring systems.


With regards to your EGR fault. Did it throw up the "restricted performance" mode, Also did it throw any fault codes with regards to the EGR's?


I have heard the horror stories at the prices they charge at the main dealers, I'm hoping I can get to the bottom of this one without seeing Jaguar

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20 hours ago, PaulT said:

The other thing that causes RP is a partially blocked fuel filter.

Hi Paul,

I have changed the fuel filter to a new OEM part 2 days ago, I still have the RP mode.

I am just waiting on the Oil I ordered to arrive to do the Oil change then I am booking it in the have the DPF cleaned professionally to eliminate it from possible causes.


What I find strange about all this is that I am only receiving the P1247-00 DTC for "low boost pressure". Surely if one of the sensors/solenoids were to be going faulty or that the DPF is starting to block then it would throw up the corresponding DTC.

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  • 3 weeks later...

I had a similar issue with Restricted Performance recently and eventually found out it was the DPF that needed cleaning. Details on this thread: 

Restricted Performance

Got the DPF removed and cleaned for £190 + VAT, which includes a 12 month guarantee, by these guys - there are branches in other areas I believe: 

Blocked DPF Cleaning Service, the UKs fastest & most effective - UK DPF

The thing about DPF cleaning is there are different types, and if the method used previously used the type of cleaning where they heat it to 1000 degrees or so in an oven, it will burn off the soot but not the ash so if you have a heavily blocked DPF, even removing it and cleaning it might not have worked correctly if they didn't use the most effective method. 

I'm no expert but this worked perfectly for me and the car drives like new now with no fault codes at all. Too much to go through here, All the info/history is on the thread link above, I know it's a long read but I can highly recommend this especially as it comes with a warranty. Have a read and see if it looks similar to your position. 

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