I hadn't heard about the GPS issue, but found this report about it: http://www.ciras.org.uk/report-library/train-operations/52131-issue-with-opening-class-377-

I hadn't heard about the GPS issue, but found this report about it: http://www.ciras.org.uk/report-library/train-operations/52131-issue-with-opening-class-377-doors-on-the-thameslink-route/ http://www.ciras.org.uk/report-library/train-operations/5213... I see it's from Jan '14, do you know if any improvements have been made since?