I have a 2013 Fiesta ecoboost 1.0 100bhp, I bought it a month ago secondhand well looked after car.
Last week the coolant feed to the turbo (metal 90deg elbow) rusted through a hole and dropped all the coolant out while I did some spirited driving... No fault light, no coolant temp warning, just cooked the engine..... When I slowed down I could feel the engine hesitate and splutter, I puled over and the engine stopped.
Got it recovered to a local garage to be told they see lots of these with the same issue, the garage tried patching the turbo feed pipe, filled it with coolant again and tried to start it, at that point the coolant bottle started bubbling up, pointing to a head gasket / head is warped.
So to save another horror story of spending thousands on a rebuild that might not work I sourced a nearly new engine (only 20K on it). slightly newer coming out of a 2018 fiesta 120bhp version. The dismantler told me its the exact same engine, though there are a few different engine codes, the difference in bhp comes from the ecu not the block.
So got the engine fitted, it looks identical, has all the same sensor locations etc...
The engine fired up no problem, took it for a spin, straight away it feels sluggish. When you put the ignition on it displays an engine malfunction message on the centre console, and displays a spanner in the clocks.
Reading the codes I get a p0237 - Turbocharger Boost sensor A Circuit low error.
As soon as you clear the code (with the engine off the code comes straight back on...
I have done various test and cant get to the bottom of it. With the code coming on before I even start the engine I think its wiring / sensors related.