start stop not working cant turn it on light stays illuminated

[g3org1n4]

My 2013 ford Fiesta 1L ecoboost's start stop isnt working, the button to turn it on and off just stays illuminated when pressed, you can turn the light off when the ignition is on but as soon as you start the car the light comes on and you cannot turn the light off, and therefor the start stop isnt working. 

any advice 

thanks  

[iantt]

There's a fault in the stop start system if the light stays on, you need it checking out to diagnose the fault.