Hello everyone, I had an inquiry about my 2011 Jaguar XJL Supercharged having a few issues.

Was merging onto a highway when the car suddenly downshifted into first gear @ 80kmh. RPM's did not seem to be too high but car was still heavily unsettled.

Now, the car won't shift out of first gear, and is showing a P2704-07 transmission fault as well as multiple seemingly unrelated module faults.
Electronic dashboard now shows "Gearbox Fault" as well as "Coolant Level Low" (despite checking coolant levels to be in well order).

Does anyone have any indication as to if this a major fault? I'm suspecting it may have something to do with the battery. Almost certain there isn't a mechanical fault, rather an electrical one.

 

P2704-07 Transmission Friction Element E Apply Time Range/Performance - Mechanical Failures

• Gear Ratio Monitoring. Mechanical Failures

• Check and correct oil level. Clear DTC. If code re-detects suspect Transmission (mechanical) internal fault. Install a new Transmission as required, refer to the warranty policy and procedures manual if a module/component is suspect.