Thanks for the response and also the photo of the sensor. Does it have a part name that I could order? Am I right to assume that as the gearbox seems to behave normally even during this problem that the van os ok to drive?

Hi there, I wonder if anyone can help me with an issue that's recently just developed on my 1996 2.5l auto diesel Ford Freda. A few miles after starting my van, the rev counter sometimes moves erratically and can drop to zero and which point the Hold light begins to flash. The problem often corrects ...