Engine Malfunction Service Now

Hi all,

My 2013 Focus (2.0 Diesel) has recently had "Engine Malfunction Service Now" message pop up. I took it to Halfords who cleared the code but said "we've cleared the code, but there was no fault to clear - it could be a voltage imbalance or a flat spot on the battery".

It was fine again for 2-3 weeks then when I switched the engine one - same message again. I did the 'press the brake / accelerator trick (service oil complete) but that only cleared the message once. I turned the car off and on a few times to make sure and it came back.

I also now how an orange engine light come up to go with the 'information' orange light, suggesting it could be getting worse, or there's something else.

I'm sure I'm not the first one to have this issue, so are there any suggestions (note I bought myself a code fault finder, but it's generic and doesn't cover Ford specific ones, apparently).

Edit: If it's relevant, I've done over 129,000 miles, and (obviously) it's a 13 year old car.

Edit 2: AI Suggesting it could be early/mid-stage DPF loading — not a random fault. As it's a diesel and I drive it 23-30 mins to work on a dual carriageway and back. My partner had same issue on a Ford Kuga 2010. Suggestion is I drive it 30-40 mins no stop in a lower gear to clear soot levels.

Edited 1 hour ago1 hr by JohnPAB