Hi everyone, I’m hoping someone could please help me (not a huge car expert).

I have a 2018 1.0L Ecoboost Ford fiesta (21,000 miles). Recently serviced with Ford (June 2025).

I drove the car for ~2 hours without any issues yesterday, but before I stopped off at home I decided to fill the car up at the petrol station.

On the way back home from the petrol station, I noticed the check engine light had turned on. After turning the engine off and on it was still there. No limp mode or anything like that.

I had a notification in my Ford app which says:

Your Service Engine Soon alert is on because of an issue with the emissions system. This may cause reduced engine power and fuel economy. 
 

Any ideas what could have caused this? In particular due to it mentioning emissions.

I have a friend who’s a mechanic coming to look at it over the weekend but just thought I’d get some opinions here as well.

Many thanks!

Aidan

Welcome?
The "Ford App" (our vehicle is far too old to have it) sounds like a great way to generate service work?

There should be fault codes (but if the fault clears, they need to be read when the check engine light is on.
Forscan is our preferred free software but you'd need a lead at about £30 or the Bluetooth dongle which can't program, as generic devices and even some "professional" ones miss Ford specific codes.
Only by recording the specific codes can some sort of diagnosis be started (or take it to the dealer and be charged a fortune just to read the codes?) 

19 hours ago, AidanG said:

I have a 2018 1.0L Ecoboost Ford fiesta (21,000 miles). Recently serviced with Ford (June 2025).

Just on a side issue, are you aware that with an 8 year old 1.0 Ecoboost with very low mileage you should be looking at replacing the wet belts in the next few months ?

The maximum age for replacing the wet timing belt is 10 years, but very many cars never reach that age especially those with low mileage.

A common issue I've experienced is oxygen sensor, but, as already said, many possibilities which need codes read.

Interesting that this has come up after a recent service though. Overfilling with oil could cause emissions related issues and the 1.0 ecoboost is tricky to fill to the correct level.

 

You might find the purge valve is sticking open and leading to overfuelling if you've got a full tank.