I just replaced replaced the battery on my 2007 XJ8 after It failed to start. Once the new battery was in I got several bogus codes that come up when turning the key to the start position. When I try to start it it doesn't do anything, no crank, no start. Everything works in the car. If it was an immobilizer issue it would still crank. Correct? Please guys any help would be appreciated.

 

First of all, was the new battery the correct one for the Jaguar? Secondly, were the battery terminals clean and snug? Also, verify that the ground terminals inside the trunk (boot) are snug.

 

Yes. The battery is correct. I only hand tightened the terminals but will wrench them in tomorrow. Thank you.

 

I had this happen to me in my 2006 LR3 (which uses the Jaguar AJ-V8 engine). The terminals were not tight enough. They would draw voltage and power the systems of the car, but the connection wasn't good enough to fully engage the starter motor. Once they were tightened down (and you should clean the terminals for good measure), everything worked.