Fiat Marea Diesel Engine Power Loss

The symptoms you describe – reduced power, check engine light, rough running, and jerking – are classic signs of a lean running condition. A faulty injector could indeed be the culprit, starving the engine of fuel. However, before jumping to that conclusion, consider other possibilities. A failing mass air flow (MAF) sensor can cause the engine to think it's getting less air than it actually is, leading to reduced fuel injection. Similarly, a malfunctioning oxygen sensor could provide incorrect feedback, causing the engine to lean out the mixture. An EGR valve stuck open can also mimic a lean condition. Do you have access to an OBD2 scanner to read the error codes? That would give us a clearer direction.

Thank you for the comprehensive reply. I do not have access to an OBD2 scanner myself. Would you recommend taking the car to a workshop for a diagnostic check then?

Yes, given the potential causes and your lack of diagnostic equipment, a workshop visit is advisable. Think of it like this: you suspect a leaky pipe in your house, but you don't have the tools to investigate. Calling a plumber (in this case, a mechanic) is the most efficient way to pinpoint the problem and avoid further damage. It’s more prudent to get a professional opinion rather than risk misdiagnosing the issue and potentially causing further harm to your engine. It does sound very much like a fuel injection issue though.

I appreciate your advice. I took the car to a workshop, and it was indeed a defective fuel injector. The total repair cost was 515€ Thank you again for your help.