My Touran 2.0 TDi (05 reg) stopped without warning while still at a garage, just after a service. 'Key immobiliser' message appeared after a couple of seconds. Now it wont run for more than 1 second. Info on the net leads me to think it's likely to be the coil round the ignition key barrel, can anyone help with how to check and/or replace this? Thanks in anticipation!