UK Ford Repair Questions? Ask a Mechanic for Answers ASAP
Hello, I hope the following assists you.
You don't mention what year car this is but if it is a 1998 to 2005 model then the fault will be due to the vehicle speed sensor failing. The sensor is on the gearbox just where the right hand drive shaft comes out, it has three wires to it. This sensor supplies the signal for the speedometer and the engine management also uses the signal for calculations, as the signal is missing this is detected by the engine management hence the amber MIL comes on. This is also the reason for the engine jerking as the engine management can't detect the car is actually moving.
To change the sensor requires access to the underside of the car, remove the small roll pin that holds the sensor then disconnect the electrical connector and then pull the sensor out. Both the roll pin and sensor can be quite tight.
Let me know if I can advise further on this and I'll reply as soon as I'm able to.