2004 XJ8 132000 miles. Bought it new.

Couple of days ago the car lost power and would only go about 15 mph. Engine was smooth, though. The orange and red warning lights in the speedo bezel lit up and the traction icon and engine trouble light lit up in the tachometer bezel.
The messages read:
1. Engine systems fault
2. Emergency brake fault
3. DSC fault (the traction icon thingie)


I was in a 25 mph zone in my neighborhood so I drove for a mile, stopped the engine, waited 30 seconds, started it up and all was Ok! Messages and warning had disappeared. I drove slowly for 20 minutes before stopping for the night.

Next AM I checked vital fluids and all was perfect. Drove 2 miles and it happened again. Repeated the engine OFF and ON again but now it immediately went back into warning lights and limp mode.

This problem is above my pay grade. Ideas? THANKS.
Norm

 

Battery

 

I would almost bet money on it being the Throttle Body, more specifically the throttle position sensor.

If it threw a check engine light, of which it may not have, you can read the code and that may guide you.

I had this happen very intermittently and over time much more often. Replaced the throttle body and it completely fixed it.

This happens because the gas pedal and throttle body are "drive by wire", so they communicate electronically. If the throttle position sensor gets a reading that doesn't look right, it immediately puts the car in limp mode with these three messages and the car will not accelerate at all. The car does this to protect the driver since it doesn't know if it's getting a right or wrong reading. Often restarting the car will clear the message and it might ride fine for another 1000 miles before it just happens again.

I changed it myself on my XJR which is more of a pain than on the non-super charged engines.

 

Oh and just cycle the car on and off four or five times and it will likely reset itself. Also opening and closing the hood also has helped it go away for me before.

It was the most aggravating problem for me, made me want to throw the car out of the window until I fixed it.

I have a 2005 XJR with 140k miles.

 

Thanks for the suggestions abonano and Mike!

I did go ahead and replace the battery since the old one was original ... 14 years! And now the car runs fine with no limp mode. However ... it still has:

1) Engine check light is on, and,
2) Parkbrake fault is reading in the info center.

At least the Engine System Fault and the DSC fault have disappeared.

I've started the engine about 4 times and the same messages appear. I wonder if my indy shop could cancel the messages and all will be fine ... at least for a while? I assume a code reader or computer hookup could tell what the problem is. I've never bought a code reader.

I'm going out of town for a few days so will deal with it when I get back.

 

Mike, I just now opened and closed the hood ONE TIME and the engine check light disappeared! But the Park brake fault is still there.

I cycled the engine on and off a few times and also opened and closed the hood a few more times but the park brake fault is still there. At least 3 of the 4 issues are gone ... for now.

Weird stuff.

When we return from our vacation I'll see about the TPS.

THANKS!

 

Usually after a battery disconnect you have to reset the electronic parking brake.

 

How do u do that?

 

abonano,

I spoke before I did a search. Found the procedure for reseting the emergency brake.

All is fine now! No faults, no warning lights!

But, to be safe I'll probably replace the TPS after my trip to Maui.

THANKS for your help guys! This is a great forum.

 

Yesterday I had exactly same happened to my car. After restart it worked fine, but it did not last long. In 5 to 10 kms it did the same thing. I restarted the car once again (several times) and the check engine light remained on the dashboard, although vehicle worked fine.

When I got home, I plugged cheap OBDII Bluetooth reader and examined the fault codes by Torque Pro application. There were two fault codes: P0121 (current fault) and P1111 (pending fault). I cleared them and checked again. This time there was P1000 as pending fault. I did nearly 100 kms after it on the same day - nothing happened. Everything works fine. Check Engine light disappeared, nothing illuminated whatsoever.

Battery seems to be OK (never had any problems with starting the car on any day), connector on the TPS is solid and clean...

Mine is 3.0 version, so the TPS is same as one on any 3.0 Mazda (including Tributes), so i can get this part pretty easy, but I am not sure what to do now...

 

The 'DSC Unavailable' fault which disappears after the engine is stopped and then restarted is a classic symptom of poor battery condition. I used to get it sometimes with mine if I left the car unused for a week, the car having its original 2008 battery. I cured it by using a CTEK charger/minder which I leave on all the time the car is in the drive.

(I have no connection with CTEK other than being a satisfied customer).

 

 

+1

 

P0121 is TPS failure

 

I had the same thing happen to me. Car seems to work fine but from what I read here this will be short-lived so I have ordered a new TPS. BTW, what should these cost? The market seems flooded with Chinese made TPS. Has anyone tried these?

 

same thing happen to me and it was the Throttle Body,my indi changed the whole the Throttle Body not just the sensor,maybe he didnt have to,anyway it runs perfect now

 

There has been a post here when a non OEM TPS was fitted and would not work.

Owner opened it up and found that it had only one track when it should have two!

Excelsior- I see that you live in Beverly hills so I suggest that you

fit a Denso TPS ? $150 lol

 

Ultimately that's what i decided to do and have ordered the Denso part rather than take a chance.