Engine Speed Sensor Fault/location/replace

Hi All,

Driving on my way in to work this morning my car went into limp mode, flashing engine light, so I pulled over and scanned the car with VCDS. It indicated an Engine Speed Sensor fault. I reset it and the car ran fine after that.

I have noticed this error a couple of times now so am thinking this is what could be causing the loss of power issues I have been having. Since the car was losing power with the relay inder the dash clicking away merrily quite badly this morning. And it did it at the moment the engine light came on.

Anyway, question is does anyone know where the speed sensor is, how much they are and how hard are they to replace?

Thanks all.