Hi,

I acquired a 2009 plate Fiesta 1.4 diesel that had been sat for 2 years. Managed to get it through it's MOT but the engine judders and I lose power when going over 2k revs before it goes into limp mode. I've cleaned the MAF filter and I'm replacing the fuel filter this week, but can anyone suggest next steps should this not resolve the issues? Think a fault code P0125 came up?

https://www.autozone.com/diy/diagnostic-trouble-codes/what-to-do-about-code-p0125#:~:text=P0125%3A Insufficient Coolant Temperature for Closed Loop Fuel Control&text=The P0125 code is a,time after starting the vehicle.

That's a petrol specific code.  Either misremembered the number or a red herring shown on a generic code reader.

So as an update, I've replaced the fuel filter and it ran way better for about 20 minutes, tried to take an a road home and the engine light has come on again and again limited to 2k revs. Does anyone know of next steps please?

I'd be tempted to suspect EGR valve sticking

Is it an easy fix? Trying to avoid putting too much money into it considering the age of it

It's an easy fix but don't be tempted to fit a cheap copy part, fit genuine or it won't fix the issue

As its been standing for two years, I would be checking the new fuel filter to make sure it isn't blocked up again, especially as it drove ok for a while after the fuel filter was changed.

Vehicles that are left standing can suffer with something called "diesel bug" (Google it). This is caused by a biological growth that forms in the bio fuel added to diesel. If the filter is covered with a black slimy sludge then this could be your problem. You can get additives that will kill the growth. This is fairly common on agricultural equipment, which is often left standing for ten months or so each year.