Recently went out to warm car up, when i came back gearbox fault appeared on the dash and the car had gone into limp mode, ran fine 2 days prior but we had a heavy rain the day before. I see no evidence of water leakage on the tcm as some suggest. These are the codes i get with my simple obd reader, p0300, p0301, po305, p1316, p0420,p1251, p0706, p1796, p1000, the car has given very little trouble since i purchased at 24,000 miles. With these codes i have decided to do a tune up before anything else, plugs, intake gaskets, both o2 sensors. Does any one think this is the correct approach to start. Also code p1796 indicates the can controller is off. What does that mean?

 

These mention P1796 but show a couple of sources for the error

https://www.jaguarforums.com/forum/x...796-help-1122/

https://www.jaguarforums.com/forum/x...43/#post634825

Could be worth checking the TCM connections just in case.

 

Seeing as you have the P1000 code I am guessing the issue is intermittent and maybe most of the codes you are seeing are older stored codes. Maybe clear all the stored codes and see what comes up and start there.

 

If you haven't resolved the problem, check the battery voltage, then connections to ground and positive. These cars are very sensitive to low battery. check it on volts dc when cold, 12.6v (anything under 11v could be a problem). Start the car, should read 14.2/15v or close, then tapper of after a few mins.to 13v/13.5v give or take depending on battery condition. If it is low check it at the alternator(large post) as the cable could be deteriorating.

 

Ok, so I finally did the tune up, all six plugs and front O2 sensor, when I started it up the engine ran much much better. Now I have a new warning on the dash that says engine system failure. Still have the P1796 code that I found on the internet to mean the CAN Cir bus is off. Any ideas, and how can I get it out of limp mode short of going to the dealer and paying $150 just to drive it on the lot. Thanks

 

Just read that CAN stands for Controlled Area Network. The first solution given was to check fuses, but no specific one was listed.
Or
It seems that it could also be a kick down switch depending on the model year.

What is astonishing is the lack of information out there on this code, despite several people posting issues with it.

Please report back when you find a solution! Hopefully someone can figure it out.