Update:

Same issue with all the fault codes as before. Further looking into it, a coolant hose had a very small leak and caused moisture in the throttle tract (track).

 

Wow, didn't this happen to you almost exactly a year ago?

 

My car yesterday shut off 4 times in a 24 hr period with resets each time, I didn't have my code reader at the time so I just reset the system, no rain, clear day in the 70s...I am getting pissed...taking it in soon, just a hassle.

 

Most relatively high-end vehicles these days have some form of limp-home or restricted-performance built-in feature which supposedly protects the engine from catastrophic failure. But I've never seen even one complaint of this feature kicking in on the forums for the other autos that I own or maintain for ourselves or our daughter (including Lexus, Dodge, Jeep, and Chrysler). Jaguar's hair-trigger for setting off these modes is close to being ridiculous. What is responsible for this? Is it a design flaw? Poor seals to the throttle body? An inability to tolerate even a microscopic amount of moisture? This is one of those events that until it happens to you (especially on the freeway at 70+ mph), you don't think it's a big deal. But boy, is your mindset ever changed once you get nailed with it....

 

Possibly one of the more recent calibrations (software versions) would help.

Turns out Lexus use the same PCM as the S-Type so keep an eye out for similar issues in due course!

 

I've never read a single comment on the primary Lexus forum that I frequent concerning a Lexus suddenly throwing itself into limp-home mode or restricted-performance mode for any reason whatsoever. Been a member of that forum for more than six years. If it's an issue with Lexus, even just a small one, it would have been reported on that forum long before now....

 

I'd think only the large ones would need such a complex Denso PCM, but makers seem a bit reluctant to disclose who makes what parts!
Maybe they just let jag owners debug the code

 

You may be right!!

 

Bull27: Correct. My vehicle is being stored and maintained by my family (currently deployed). When they conducted the weekly checks and road test, the same fault codes were displayed. Vehicle was then towed and diagnosed by Bellevue Jaguar. BTW a very good dealer to work with, as we have other Jaguars serviced by them. Mass Airflow Sensor (Meter) was replaced along with the throttle body. Select Edition covered this part/labor. Cost incurred on my end was for the leaking coolant hose under the supercharger (I have not confirmed the actual part).

 

Phew, good thing you have that Select Edition. This is very interesting though, did they replace the throttle body last year or just clean connections and re-seal? Take car of yourself over there man.

 

Took my car to the local jag dealer, Alpine Jaguar. Told the service writer what the problem was and gave him all the codes I got. I let him know that I erased the codes because the car would not drive.

They had my car 3 days, drove it 60 miles and burned 1/4 tank of gas and guess what no codes and they won't fix it until the codes are in the computer...

Needless to say, I was pissed...

 

Did you also give them all the freeze frame data? What about the misfire counts? And the fuel trims? Plus the monitor statuses? And so on. When you cleared the codes you cleared everything.

I do not understand why you think it sensible for them to try fixing something that isn't broken when they receive it. hmm, that's not quite what I mean.... are you happy to pay them for work (no chance it'll be covered by a warranty in these circumstances) even though they have no obvious way to work out if they've tinkered with the right parts? Are you happy that they replace parts just hoping they're the right parts? Even a throttle body at say $1400? If you are happy, go right back. If you can figure out specific work you want them to do (at your risk that it's not the problem), go back.

Alternatively, you said the problem came right back multiple times so how long before it'll be back again? Take the car in then.

 

I've done some additional research on "limp home mode" failures and causes that are not necessarily specific to Jaguar. We all know that moisture in the throttle body provokes "limp home mode" in our S-Types in a heartbeat. But I've also learned that in some Japanese and German vehicles built in the late 1990s and early 2000s, "limp home mode" can be caused by running your fuel tank down to nearly empty, especially during the hot summer months. The reasoning is that with most of today's fuel pumps being located inside the fuel tank, a full tank of gas helps to keep the pump cool during operation on hot days (defined as outside air temperatures above 80 degrees). When you drive on a nearly empty tank on a hot day, the pump does not get the cooling effect that it needs, it heats up beyond its normal operating temperature, the sensors pick up on that, and BAM - the ECU makes the decision to slam the car into "limp home mode"....

The solution? Fill 'er up before you get down to 1/4 tank of gas. Several owners of Japanese and German cars who had experienced "limp home mode" were talking back and forth on a car forum and figured out that they had all been driving on hot days with nearly empty fuel tanks when they got hit with "limp home mode". Once they changed their habits and began to fill up before getting down to 1/4 tank, no more problems ensued....

It may or may not apply to our S-Types, but it certainly is food for thought....

 

It sounds a bit obvious I know Bull 27, but have you looked at the battery terminals? If there is a white excrescence around them (sulphation) you might have a subtly intermittent connexion. If not, try and twist the connectors by hand using all the force you can muster (no tools). If you can't shift them, they're ok. BUT, not finished yet --
follow the super-thick battery cables wherever they go, and when you see a connector, make sure its reasonably tight. There is a ground strap always somewhere between engine and body, make sure the connectors are tight.
Explanation:--
On a 12volt system, even the slightest bad connexion can annoy the control computers (there are many!) making them issue a list of faults which they have calculated as most likely. Remember also, while driving, the alternator is charging the battery, you might have the headlights on etc., resulting in a fluctuation load/charge condition. Even a slightly bad connexion can spark unknown to you, putting high-ish voltage glitches all over the wiring. Computers are VERY sensitive to these kind of glitches! So... Also check the tightness of the main output terminal on the alternator.
Putting it simply, the whole lot must be in apple-pie order.
Leedsman.

 

Out of 256 DTCs in the 2003MY DTC file I found 39 limp homes and many reduced engine power ones as well. Things need to work to avoid limp home.

 

In the references to using silicone on the trottle body connectors, are these refering to silicone sealant (RTV) or to silicone grease? I would assume silicone grease since RTV would make it almost impossible to remove the connectors in the future without damage. Any comments?

 

I agree that RTV in this application would be a big mistake....

 

Leedsman: Im good man, my throttle body issue is in the distant past.

Ok so maybe some people got up on the wrong side of the bed here. Silverstar said he wrote the codes down, and I am assuming since he is posting on this thread that they match the ones we all got with throttle body issues. So the battery and the 39 other other reasons for limp home mode would be rendered obsolete.

Does the vehicle not store the history of codes, even if they were erased by a scanner? I was under the impression it does.

This freaking limp home BS is dangerous. My car would NOT leave that dealership unless it was fixed according to the codes I pulled. Obviously this is going to come back, when, who knows. Maybe when he is pulling out onto a busy road, or maybe when he is on the highway in front of a tractor trailer. Point is, you dont take the chance if the problem is CLEARLY documented throughout the multiple pages of this thread as well as others.

 

Heck we're on page 8. I'm not gonna try to guess which codes he saw and anyway that wouldn't tell me all that other data I listed.

When cleared, the codes (and data) are gone forever. This is changing (by law) in future OBD such that the only way to clear a code is for the PCM to see that the problem is cured and the PCM will then clear it. A scan tool will be unable to clear the code. Be afraid.

 

Lets see I gave them all the codes and there were other items that needed to be addressed that they didn't take care of. Last time I got the codes I attempted to have the car towed since it doesn't drive when it goes into limp home mode. I waited 1.5 hours for the tow truck, then when they got to the Jag dealer the gates were locked and there is no night drop off, so they brought the car back to me at my home...So Alpine expects me to have a failure and get the car towed there during service hours, (yeah right!!) and now of course it doesn't throw the code until I am a trip on the highway and have it freaking die on me..how convienent. Sorry I was expressing my frustration....maybe when the car gets rear-ended on the highway after it dies--it might have a malfunction and clear the codes!!! lol.

Bull27 Thanks for your support. It is dangerous!!