Mpg dropped off of a cliff… help!

[Matthewappleyard]

Hi all

 

looking for advice and or help

currently own a 2018 plate st line focus 1.5diesel which up until recently delivered on average 51-52 mpg on my daily commute. Over the last few weeks this has dropped off of a cliff even in eco mode. I’ve had this checked over at a local trusted garage which have investigated the usual culprits namely break binding, misalignment of wheels and tires and even checked the injectors performance management  systems electronically. 
has anyone else encountered similar issues and if so how do I go about resolving them 

[unofix]

Your car is probably stuck in the "incomplete regen" loop.

Get the engine nice and warm and take it on a 30 mile trip down the A1 (or A19) at a constant 60 mph. The car will restart the regen and complete the cycle. On the next trip out after that the MPG should start heading back to normal.

My car has done it twice, its the price we pay for driving diesel and doing too many short trips.

[isetta]

Does that mean the engine oil will now be diluted with diesel ie. oil level gone higher and oil thinned by the diesel

[unofix]

Never had problems with my oil level or being diluted but I guess it depends how many times the regen has failed.

[Wino]

1 hour ago, Matthewappleyard said:

Hi all

 

looking for advice and or help

currently own a 2018 plate st line focus 1.5diesel which up until recently delivered on average 51-52 mpg on my daily commute. Over the last few weeks this has dropped off of a cliff even in eco mode. I’ve had this checked over at a local trusted garage which have investigated the usual culprits namely break binding, misalignment of wheels and tires and even checked the injectors performance management  systems electronically. 
has anyone else encountered similar issues and if so how do I go about resolving them 

Is this a mk3.5 Focus or a Mk4 ?