I am getting an engine warning light occasionally when starting or soon after (a few seconds).. This happens (say) one time in 10 or 20 starts. I have a new battery fitted, and the additional earth wire. I have removed, checked and replaced the earth wire to the body. I can clear the fault with an android tablet. It shows up as a p0300 error which (on the web) states computer software problem (Very helpful!!!).
Any ideas as to where to look. I think it must be a wire/plug problem as there are no other problems and the car drives well without problems with or without the "fault" cleared.

The web & cheap diag tools can be as much use as a chocolate tea pot.

The vehicle needs reading with a diagnostic tool rather than a scanner.

If the fault code that is displayed is correct its possible its suffering from a random multiple misfire.
At this point i would normally study freeze frame date, this stores a snap shot at the point an error occurred. This will normally be a good indication at what point the fault occurred and often useful date with it can narrow down the diagnostic time.

If its a misfire, it could be related to a glow plug, an injector or crank sensor signal error. even a sticky EGR valve could cause rough running on start up.
I would be scoping a crank & can sensor, carrying out a fuel rail pressure test and cylinder balance comparison test. Jaguar x-type sport gone
Jaguar x-type 2.2d sport one of my best cars ever sadly gone
Freelander 2 GS auto 2008 most unreliable ever ! gladly gone
Freelander 2 GS manual 2013 only time will tell !