Mercedes A Klasse engine running lean

I have a similar A Klasse. Lean running can be caused by a number of issues. Have you checked the mass air flow sensor? A faulty oxygen sensor could also be the culprit, as it directly impacts the air-fuel ratio. An EGR valve malfunction can also mimic these symptoms. It might be worthwhile investigating these components before replacing the fuel injectors.

Thank you for the suggestions. Regarding the mass air flow sensor and oxygen sensor, is there a reliable method to test their functionality prior to replacement? Are there specific diagnostic codes that would definitively indicate a failure of the EGR valve?

Testing the mass air flow sensor typically involves measuring its output voltage with a multimeter while varying engine speed. A healthy sensor will show a smooth increase in voltage. Similarly, the oxygen sensor's voltage fluctuates rapidly when functioning correctly; a sluggish response indicates a problem. Diagnostic codes related to the EGR valve often involve insufficient flow or valve position errors. However, given the symptoms and mileage, it may be prudent to consult a workshop for a comprehensive diagnosis. In my case it was the fuel injectors.

I appreciate the detailed information and advice. I will proceed with a professional diagnosis at a workshop as you suggested. As it turned out the fuel injectors were indeed defective. The repair cost was 515€. Thank you again for your time and assistance.