I am loosing it. I had my 1999 XK8 into Jaguar this week to check out why I kept getting lots of codes and getting stuck. They put their readers in and only found bank 2 rich. I was advised to run Techron through 2 tanks of gas first to save some $$ and see if that helps. I went to drive it 2 days ago and the car went nuts. On the dash I got Transmission Failure, Failsafe mode, Engine Failure and limp mode. I got home (barely). This is the second time in a month receiving those messages. I tried starting the car for 2 days with the same results. Today on day 3 all of those messages are gone but check engine light is on with a bank 2 rich code on my reader. I cleared that and now runs fine, but I really want this car to not get those messages and find out what is causing it. Any ideas?
Thanks
Jack
1999 XK8

 

Bad battery or bad connecton to the battery.

 

Battery is new. Terminals and end of wire clips were wire brushed prior to install.
Thanks
Jack

 

The car is displaying all of the symptoms of a bad battery. Even though it is new I would have it load tested. Additionally if the battery cables were corroded before the battery change out is possible that the corrosion is deep in the cables and unseen. These cars need a lot of power for the modules. A car will crank over just fine and start but it is still not enough to keep the computer modules happy. Sitting before starting your battery should be 13.6 volts or better and during running it should be around 14.5. 12 volts is enough for the starter.

I would check the cables just to be sure they are in good condition. You might also want to look for a parasitic drain on the battery when the car is shut off. The most common one is the little door on the ignition switch where the key goes in. If it hangs up it won't allow the computers to go to sleep mode. Also common is the glove box light and the trunk lights. Set a phone with video ability inside and close the covers and make sure the lights are turning off.

 

ECM?

 

Also, do not forget about the high voltage fuse block behind the spare tire that the positive battery cable runs into; there may be loose connections or corroded fasteners to or from this block, or the metal 'strip' fuses may be corroded or loose.

 

You sure about the 13.6 volts?

 

A Jaguar Dealer advised you to do something to save money! I'm not sure that isn't a first on the forum.

Always a good idea to post actual codes and not descriptions. Using anything other than the Jaguar DTC lookup tables can often be very misleading.

If it's P0172 and the fuel system is clean and clear then it could be the ECM receiving an incorrect signal from any one of a number of sensors (ECTS, MAFS, IATS, TPS).

Graham

 

Check the connectors on the throttle body. Pull both plugs and hose them down with contact cleaner, really get them wet, put a rag down so they will drain and do both sides on plugs. This cures the same problem on my '99. Happens when weather changes or very wet after a long dry spell.

 

Would that give a Transmission Failure message?

 

Hi all,

Thanks for input!!!!
The major issues were healed by having ASI rebuild my throttle body. Running Techron in my fuel tank did clear bank 2 running rich but now instead of code PO175 for Bank 2, Now I am getting PO172 which is Bank 1 running rich. Also going in and out of restricted mode with check engine light on. P1121 appears to have gone with old Throttle too. Making some progress. I feel this is all (except throttle body) from using my XK8 1,200 miles in 4 years.
If this was a MK2, an XK120,140,150 or an E-type, I would have repaired these issues long ago.
Thanks
Jax
1999 XK8

 

Yep, these cars do indeed seem to stay much healthier when they are driven regularly....

 

I can't get rid of these codes. Check engine light is constant and restricted performance is back and forth. Checked all connectors and air hoses. Just put in a new air filter and vacuumed out leaves, etc from filter box.
Car is running great since I got Throttle body back from ASI but getting a pop sometimes when accelerating and the restricted performance message comes on for 4-5 minutes.
Any suggestions?
Thanks
Jax
1999 XK8

 

It seems that sometimes when there is a pile of seemingly unrelated error codes that it might be the corrosion issue on the printed circuit board of the instrument cluster, a known issue.

Does anyone else think that this might be the cause? There is a service bulletin for this, "Instrument Pack Assembly--CAN Failure--Service Action S484"

What do some of the electrical guys in the forum think of this possibility?

 

I wouldn't think if that was the case, I would get the obd2 readings of PO172 & PO175
Thanks
Jax