Did a quick search but didn't see anything about this. Last week while driving a message popped up on the dash "Fuel Filler Cap Loose". I stopped and checked but it seemed tight to me. However I took it off, put it back on, and started the car and the message was gone. Drove another five minutes and it popped on again. Got home, did the same fix, and it was gone again. Oddly enough the manual does not show this as a message that can be displayed.

Anyway, next morning the message was still gone but the CEL was on. Figured maybe a vaccum leak so took it to dealer. I did not check the code. Now dealer says it is a power issue and the positive battery cable needs to be replaced. He said the cable shows heat damage where the positive and negative cables split and I will need a new set of power cables. He said that was what was causing the CEL and what was causing the message to appear. Does this all make sense? Thanks.

 

tarheel, yes, it can cause what you were seeing. Granted, normally there are other codes that get tossed first. In short, the bad cable causes the voltage to drop to the computers. THis will cause the data being transferred between the computers to more easily get corrupted, leading to erroneous faults. If you want me to get into the theory of how digital data is transferred, let me know. I bet you will also find that the car will crank over a lot better/faster after the new cables are installed. If you can, install the cables yourself. The cables are easy to replace and you can get generic cables at your local parts store. Having a second vehicle will be helpful since you will be able to pull the cables off, take them to the store, match up the cables so you get the correct cables.

 

Thanks Thermo. I feel better about what the dealer is telling me now. I will probably just let them go ahead with the repair. They are also doing an oil change and checking on a leak for me. On the bright side I am driving a brand new XF with 2400 miles on it while my X is being repaired. They tell me it will be Tuesday before mine is ready so I am going to enjoy my new ride while I have it.