I hope for some advice here (sorry for my bad English, I am Norwegian).

I have a 2012 XF 3.0:

On Saturday, suddenly at about 50 kph the engine/rpm started to jerk for some seconds, then the engine shut off. Error message on screen: "Gearbox failure", "DSC not available" and "Battery fault" (the battery message only flashed on the screen for less than one second).

Tried to start the car - will not start, just cheeks. As if it was an immobilizer activated.

Waiting 5 minutes, the car starts as normal without any error messages. Driving it on the sidewalks (I tested both R, N, D and S) and it shifts without any noise, everything works and sounds normally. After a few minutes of idling, the same happens again (engine is jerking (almost like empty for fuel) and engine is cutting off. Motor light is on and the same error messages as mentioned above in the display. I called for a recovery truck to bring my car to a workshop. When the recovery truck arrived, the Jag starts as normal (though all error messages are constantly displayed). I drive nicely on the recovery truck myself, without feeling anything unusual. No abnormal sounds.

After the incident I went to google and searched for the error messages. In different forums many people write that a bad battery can result in a lot of error messages (XF is very sensitive for a bad battery). Furthermore, it is written on various forums that corrosion on fuses could cause this kind of problem. The day after (Sunday) I go to the workshop where it is parked on the outside (waiting for repair today (Monday)). I have never had a problem with the battery. I took out the battery and charged it completely full. The battery was out of the car for over 1 hour. I took out all fuses in engine compartments, dashboard and luggage fuse box that are related to gear, engine control, abs, handbrake, brake and other that may be related. Most fuses have a small "coating" with "something". I scratched them completely to the metal to ensure good contact. Reinserting battery and starting the car. It starts as normal, no error message and no engine light. After 15 minutes on idle, with a few yards back and forth in Drive / Reverse, exactly the same happened (as mentioned above) while the car is in P. It's jerking on engine/rpm and engine shuts off. Will not start afterwards but 2 minutes out of the car and try again - start fine - however with error messages, same as before.

This afternoon, the workshop has been troubleshooting and reading the error codes. They say there are various sporadic error messages on the fuel pump and camshaft sensor. They say they are reasonably sure that it is camshaft sensor that has begun to fail. When this fails, the car will not do correct timing of the ignition, etc. They say the best place to start is to replace the sensor. I have not received a price estimate yet, but he told me that it will take some hours (maybe a day), so wild guessing he estimated price to around GBP 1000 (NOK 10.000,-). I will get the correct estimate tomorrow. It’s very expensive to repair cars in Norway (also expensive for the parts compared to UK).
Furthermore, the workshop tells me that it is a ring around the sensor that also should be replaced when replacing the sensor, BUT this was not necessary since the engine had to be removed from the car and opened to replace the ring. I find this statement a bit strange.. is this correct?

I need to decide if I want to follow the workshops advice about what to replace within tomorrow morning.

The workshop is a Jaguar workshop/dealer, but have only been it for a couple of month, and limited experience (maybe).. They have had Land Rover for some years though.
That’s the reason I want to ask here before I proceed with the suggested repair. Off course I have to pay the 1000 GBP for the repair even if it’s not fix the issue.

Anyone with similar experience, or having the knowledge to advise me one way or another? Should I ask the workshop to replace the battery first to see if it helps? Should / may I swap the ring that was mentioned or is it unnecessary?

The car has worked great all the time, this came like lightning from clear skies.

Feedback are highly appreciated

 

How old is the battery?

If it's more than 5 years old, you should replace it anyway because they don't last much longer than that, so better to eliminate the battery as a problem without wasting money since it should be replaced in that time.

Also check with a voltmeter what is the voltage when the car is running. The voltage may show an issue with the alternator.

Once you have eliminated the battery and charging system, then you can take those error codes with more confidence that they are the problem and not the system of a battery/alternator issue.