Hi,

I have a 2015 MK7 Ford Fiesta Red Edition 1.0 ecoboost 140bhp. The car has just hit the 50k mark and the engine managment light has come on. I tested it with an OBD2 reader and it turns out it was the Oxygen (lamda) Sensor Bank 1 Sensor 1 (pre cat). I managed to get my hands on one and had it replaced and cleared the code using OB2 reader. i drove about two miles and turned the car off and back on and to my suprise the engine managment light came back on, I then reset my ECU by dissconnecting the battery from the car and left it for 10 mins before reconnecting it however the light is still on.

I have read something about drive cycles and how the car needs to go through a certian number of drive cycles before the monitoring system resets and could even be up to 100 Miles. Does anyone know anything about this or anything els i could try or if this drive cycle thing is even a thing?

Yeah had the exact same with my Fiesta 140bhp 1.0 eco boost.

Hit 50k... the next day EML. Both lambda sensors had flagged. They are not cheap either to find the ones for the ecoboost took a while ended up at Jayar car parts. £150 for two sensors.

easy enough to change anyway just make sure you use penetrating fluid on them the night before to loosen the plugs for you the next day.

If you don’t have lambda sockets, make sure you have deep drive sockets and just cut the wire off the sensor 

clear the codes 

 

bye bye EML.