I have a 2004 Jaguar XJ8 which I love, until this message appeared and the car went into limp mode. . So, had it towed to local non-Jag mechanic who read ten different codes and concluded that I need to replace the throttle body and the main power distribution panel, ie fuse box C2C20225 located under the hood on the passenger side.

I checked with a dealer and a retired Jag mechanic, and they both confirmed this to be the case. However, being a skeptic, I find this hard to believe.

Does anyone have any input to help me out. The expense of replacing these items is simply ridiculous.

Some threads suggest cleaning the throttle body. The car only has 58000 miles and has performed exceptionally well. However I have noticed mileage has diminished over the past year or maybe two, rarely get near the 28 mph with long highway driving.

HELP !!!

 

How old is your battery ?, a dodgy battery can throw up all sorts of warning lights and problems, just a thought, a cheap option to try first.

 

Yes, the battery is about 6 years old and hasn't ever given me any problems. The car always starts right up without any hesitation but I will certainly bring that to the attention of my mechanic.

I'm told that one of the codes is P1251 and strong power is going to the throttle body relay but no signal is coming out. This seems to suggest a bad relay in the fuse box which seems to indicate both the throttle body and fuse box will need replacement.

Many thanks for taking the time to make your thoughts known

 

I can confirm that replacing the throttle body will fix this problem. I had an identical problem a few months back on my '04 XJR and that is how I fixed it. This is a job that you can do yourself if you are an occasional wrench turner.

I did not touch the power distribution panel. FYI.

 

Your experience is certainly encouraging since the estimates to replace both the throttle body and fuse box are really ridiculous. If I need to replace parts, I certainly will go with the TB as a first step, although two Jag mechanics are indicating it will be necessary to change out the fuse box. Presumably the short in the TB made its' way into the fuse box shorting it out.

Car is with my local mechanic and hopefully we'll get some good news before the week is out.

Appreciate your interest and input.

 

I can also confirm that it is indeed the throttle body position sensor. My first X350 had this problem within the first month of ownership, and back then (7 years ago) it was not such a common knowledge issue. It cost $1200, which really grinds my gears because I could get a throttle body nowadays for around $300 and do it myself.

 

If the battery is 6 years old. Swap it first to see what changes.

Throttle bodies are expensive.
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+1 for getting the battery checked. A tired battery is still capable of starting the car but the voltage only needs to very slightly down and you get all sorts of spurious unrelated faults thrown up.

 

If it were me, I wouldn't even bother replacing the battery. Get it checked, but if it checks out good, don't replace it with just your fingers crossed. Engine Fault, Parkbrake Fault, DSC Not Available means bad throttle position sensor 9 times out of 10. Mine was also a 2004, apparently it was more common on that year. I also wasted money replacing a perfectly good battery hoping it was the cause. It was not. If it were the battery, I think you would get a whole bunch of different lights and warnings each time. But if it's that specific combination of three, its definitely the position sensor. I don't know if it's possible to replace JUST the position sensor instead of the entire throttle body, but I would definitely look into it.

 

I recently had these warnings appear on my '04. I ordered an aftermarket throttle body from ebay for $250 and replaced it myself.....it only takes about 20-30 minutes if you are somewhat mechanically inclined. It worked great for about 3 weeks then the messages re-appeared twice. I then discovered that the mass airflow sensor was dirty and cleaned it. Now....knock on wood....the car has been running great for the last 1,000 miles or so.


Rob

 

It is possible to replace just the tps.

A lot of research on this was done some time ago on this forum

re sourcing the part and I suggest you search for the info using

google and the part no on the tps rather than the search on this forum.

Just had a look myself

https://www.jaguarforums.com/forum/s...solved-138182/

 

I had this problem and my mechanic found that there was no voltage to the throttle body valve. This was due to a faulty relay that is built into the main fuse panel, thus requiring a new main fuse panel (an $815 part). This replacement corrected the problem and the car even idles smooth (which was a problem for the past 2 years). I had 10 fault codes including throttle body and fortunately my mechanic's troubleshooting resulted in only replacing 1 part.

 

My personal solution for my 04 XJR, with 83,000 miles was the replacement of the TPS, period. Same fault codes - Engine Fault/Parking Brake/ DSC not available. Went into "limp mode" while driving once and a second time I had started the car, backed up, put it in drive (which it SLAMMED into) and the same symptoms and codes. I also noted both the amber and red indicators on the dash were lit, along with the traction control warning light.

Hope this saves some of you both time and money!

Very peculiar cars, difficult to diagnos, but so worth the ride and performance in my opinion.

my 2cents

P.S If you cycle the key, start/off 4 times it should clear the issue and take you out of limp mode too......

 

Hi,

I have 142K on my XJ8 X350 4.2 SE at the moment. I have done 42K since purchasing the car last year. I am a high mileage user and travel an average total of 180 miles per day, four or five days a week.

Great car but I've had lots of things that I have fixed in the last year. Some far easier than others.

Fixes/replacements in the last year include:
Air suspension faults - fixed by taking the compressor off the car and replacing the seals - a guy in the UK makes a great and simple kit to fix this problem - not had the problem in almost a year after the fix
Set of rear brake discs and pads
2 sets of front brake discs and pads - suspect a caliper is not working properly and hence keeps warping the disc on one side of the car
Both front hub bearing assemblies - absolute nightmare to get the old ones off as they seize to the hub leg
ARB drop links replaced due to clonking/clanging suspension noise when driving over potholes and uneven road surfaces
Coolant leaking from EGR/Throttle body preheating pipes
Auxiliary drive belt - done during coolant leak as the old belt needed changing due to visible cracking
Gearbox transmission oil and filter change/service - due to gearbox fault when accelerating up hill
Failed Fuel Injector on cylinder 5 due to split injector connection clip wire being split and shorting out - this was quite easy to fix but I had issues afterwards due to low fuel rail pressure and misfire (turned out to be a damaged o-ring done during injector replacement - had to remove the fuel rail and all injectors on that side of the engine to check and replace all the o-rings across all the injectors.
Misfire and engine vibration at between 1.5K and 1.8K RPM - spark plug issue most likely caused by driving the car with a faulty fuel injector
DSC not available, wipers move on their own, brake fluid fault - currently investigating this as it's totally random but can sometimes be triggered by activating the windscreen wipers - potentially a ground issue at the front of the car as the weather is getting colder.
Lost of headlight bulbs - maybe due to a ground problem.

I'm going to add some of my experiences to the forum at some point as I am also new to the forums but try to do most of my repairs or maintenance myself. I've also recently done a service (oil, filters etc) which is very easy on this car.

Thanks,

Chris

 

Welcome Chris. The sharing of experiences by Jaguar enthusiasts is one of the highlights of the forums. We can all give and take here on the forums

 

Hi Jazzyjags,

Thanks for the welcome. Too true about sharing our experiences. We can learn through each other.

I don't know how but my post above was actually for another thread so I'm not sure how it ended up on this one. I actually replied to a topic on high mileage and what issues/problems users have had along the way.

Thanks,

Chris

 

Hi all,

Just wanted to let you all know that I have now fixed my DSC not available, park brake fault, brake fluid low, creeping wiper issue.

It was a heavily corroded ground point on the left side of the car, the lower ground point. It actually broke off in my hand when I started to put the spanner on it to undo it. I suspect it had just got to the point where there was too much corrosion to have a decent and continual ground.

The other ground points (the single one on the right and the top one on the left) cleaned up really nicely with electrical contact cleaner and the use of a fine brass brush.

I have relocated the bottom ground point to a nearby location by drilling a new hole and using a bolt, washers and a nut. The cabling has some slack so could easily reach the new location. I will replace the bolts soon with aluminium ones as I want to future proof this as much as possible.

But this completely fixed all those issues. I hope this helps others. I will create a separate thread with pictures at some point on how I fixed it which may be of use to others.

Thanks,

Chris

 

That's great news. Glad it was something simple

 

Yeah I'm glad it turned out to be so simple jassyjags. I could sometimes trigger the problem when stationary with the engine idling by using the windscreen wipers - it would through loads of faults and then stall the car. I first got the problem when driving on the motorway at high speed and hit a pothole. The wipers started to creep and got the DSC not available, ABS light and brake fault light all on and then it all disappeared within a few minutes. Then I got it randomly a few times after that but I couldn't seem to trigger it again with anything I tried. It just seemed to throw the errors and creep the wipers totally at random. So I thought I'd check the ground points and clean them up as I've seen posts about similar issues with the points.