Don't do it without getting ALL the codes written down AND the freeze frame data for them. You do not want to be short of data when trying to fix things, else you could be putting in expensive parts needlessly.
Depending where you are, more advice may be useful. Please put your car details and at least your approx geographical location in your profile.

 

I've been cruizing the posts to stay on topic when I came across your post. Just so happens, I've had an odd experience with my 2003 S-type 4.2L. On a few occasions, when the tires have spun in gravel on a corner or such, the engine has gone into limp mode. I pull over, turn it off & restart and all is fine. This happened maybe 3 times over a period of months. Then the other day, driving on the highway @ 80 kph, I ease off at a dangerous intersection and the dash lights up with warning lights. Park brake, traction control, you name it. So I pull over and try the restart the engine trick. It restarts, only it doesn't want to reset. I try it a few times until it resets. Drive another mile & a half, slow to stop and dash lights up again and stalls as I round a corner. Now sitting in the middle of the intersecting highway, I try the restart. It works, but now the engine light is on. Now I'm afraid to back it out of the garage. Ever heard of anything so crazy?

 

Things weren't really "fine", you in effect ignored them. Reading the codes, in your case probably using a dealer, would have been wise.

If you're lucky, your problem is a failing battery which is now so bad the car modules can't get good power. If you're unlucky.... off to the dealer.

 

To echo jagv8's comment, change the battery first. Even a minor reduction in battery performance will negatively affect the sensitive electrical control systems. Having run into this twice now once on our S-Type and the other on our X-Type it is the best place to start.

I did see a recent post on the forum regarding places to buy that were very economical - Worth a search.

 

The battery is new when I bought the car just more than a year ago. The car is garaged always. I am going to check the battery and connections, although a quick glance yesterday showed no corrosion on the battery posts. If not the battery or connections, it would likely be an electrical problem downstream. I have had problems with electrical connections, but mostly with lights. The transmission was removed to replace the rear engine seal some months ago. I wonder if an electrical connecter was not connected properly? Yesterday the car ran perfectly, but failed after highway driving 30 km (20 miles) in cool weather. In fact it even cleared the engine light on its own before failing. When this occurs, all the warning lights come on, the engine runs near idle, occasionally stalling completely. It will rev up a very small amount if I press down the throttle an inch or more, I am just able to keep moving on the flats. So I have no choice but to pull over and try something. It does not sound like it's missing either. Thanks for your comments.

 

Thanks to RobGardnerBlack & JagV8, I went back and pulled the negative battery clamp off & low & behold it was snug, but not tight. The battery post and inside the clamp had oxidation, but no other corosion build-up. Took the neg cable completely off, cleaned it up & reinstalled. Removed the positive, cleaned it up as well, but it had been good & tight. Covered connections with petroleum jelly and all problems are now cured. Even the transmission shift performance is just like the day I bought the car. So the ZF transmission shift solenoids must draw a lot of current, as the stalls & other sensor failures occured during transmission shift changes. My faith in my Jag is renewed, but not in my Jag dealer. Their mechanic failed to sufficiently tighten the negative battery clamp after last working on my car and it caused me months of anguish.

Big *****, I would go into your local auto parts dealer that does scans and have them run it. Along with the advice from the above named, it was what helped direct me to the problem. My scans showed multiple sensor power failures.

 

Excellent! I love a happy ending.

 

HEHE don't we all brother don't we all!!!!

thep, be sure to check the water level in the battery as well, if low add distilled water to bring up to level.

 

Excuse me while I pry my foot from my mouth. The car failed again, going into limp mode 3 times before reaching the auto repair shop. Each time I had to let the car cool a few minutes before starting again and driving several city blocks. Codes say throttle body sensor. Not good. Apparently the throttle body was too hot to touch when the mechanic pulled the engine cowling off. I was told that if the sensor does not now come separate, the whole throttle body needs replacing. Maybe 4 grand to replace. Hard to believe this could happen to a car with 75,000 km on it. Anyone know of anywhere to get a separate throttle body sensor for a
2003 S-Type 4.2L, cheap?

 

It shouldn't be anywhere near $4,000 even at a dealership. But it could very well approach $2,000....

 

Are you SURE the person diagnosing the problem (as TB, in this case) REALLY knows these cars properly? You could spend a lot of $$$ finding out he doesn't. What actual temperature was the TB? It's on the engine so you'd expect it to be hot!

Even IF it needs fixing, a TB can be reman'ed for a LOT less than has been said so far. Do some research if you want to save $$$.

 

Yes, I did check this forum, as well as 2 British forums to see what the consensus was. Apparently throttle body sensor failures are quite common. In fact there are persons wanting to start a petition for recalls. Costs range from several hundred to $2800 as I recall, depending on the model. There is a repair service in central US and refurbished units from California and England. I found these during a short search of the net yesterday afternoon. If anyone can recommend one of these services, it would be greatly appreciated.

Kind of funny, but not. One fellow paid the $2,800 US for his throttle body replacement and immediately put his car up for sale. This type of thing is bound to hurt Jaguar. If they were smart they would take some positive action, but of couse we know that is unlikely. It hurts to say, but I am considering repairing it and selling as well. I would really miss the good parts, but certainly not the bad.

 

I completely understand and sympathize with you. The throttle body systems in these vehicles appear to be a very real weak link. And far too expensive compared to throttle body costs in general. Fortunately for us, ours was replaced while the car was still under the factory warranty last May. The car had less than 30,000 miles on it at that time....

Good luck in whatever you decide to do. And keep us posted on your situation....

 

Oh, ffs! Jag made vast numbers and a few people moan (not directed at a specific person) along with the ones who think a broken window regulator on a 5 or 10 year old car is a lemon law category. There are more misdiagnosed TBs than actual faults. Jag even issued a notice about that. Quote: "One fellow paid $2800 ..." - yeah, there's always one. Doesn't mean the rest of us are so pathetic. Have a look at TB problems on other makes of car. You'll have to search for other names as they're also called ETC (yes, really) and so on.

 

Nobody's moaning, pal. These S-Type throttle bodies seem to shut down at the drop of a hat (or more accurately, a raindrop). When it happens to you, let's see how you feel about it then....

 

Some fail. Or the seals are wrongly installed so they leak (sound familiar?). Of course I'll be fed up if mine goes wrong. Ditto the tranny or engine or PCM or anything else major. But the actual percentage of genuinely failed TBs on the S-Type is small. Thankfully we don't drive a car made by Toyota! (And yes they do have TBs. Emissions laws are making them almost mandatory. Reckon voting against the laws would work?)

 

Good discussion. I just received a call from the mechanic and they looked further into the situation, discovering that a hard code (don't yet know the number) shows that the source of the problem is the shift control module. I have had problems with it not going into manual mode lately, but did not relate that issue with the fuel injection system. Apparently the shift control module puts the car in limp mode which restricts throttle operating range and can cause a throttle position sensor error message. I told him to proceed with the repair of this control module, which is considerably less expensive. We will find out if this solves the problem.

So JagV8 may be correct, but "search" for the threads under "throttle body sensor issues" in this forum for an interesting read if you're interested.

 

Hope it works out as inexpensively as possible for you....

But I still say these S-Type throttle bodies are far too problematic. I've participated in a number of different automotive forums over the years (Dodge, Chrysler, Jeep, and Lexus), and none of those members have ever had to replace their throttle bodies under any circumstances except for car crashes. Clean them, yes. Replace them, no....