GUIDE: Reading error codes
The Bentley Eight uses a Bosch Motronic ECU which, helpfully, allows you read error codes to determine any issues you may have. I'm led to believe that not all models have the black square Motronic button so check first to see if you do before following the guide.
Step 1 - Open the passenger door and you will find a small button by the door shut. Support the front of the fuse panel (which is under the glovebox) and press the button. The fuseboards will be exposed as shown in the pictures
Step 2 - Check that you have the square Motronic button on the right hand side of the fuse boards as shown. You should also check that the fuse B1 in the left hand fuseboard is fitted (it is a 20 Amp fuse called 'Gear Selector'