Mercedes CLA Diesel Fuel Regulator Issue

A faulty fuel pressure regulator sounds plausible, especially since the issues began after you replaced the fuel filter. An air bubble could be trapped, or debris might have entered the regulator during the change. The check engine light, rough idle, and reduced power all point to fuel delivery problems. Have you checked for specific error codes using an OBD2 scanner That might give you a more precise indication. Also, inspect the fuel pressure sensor wiring and connections to ensure they are secure and undamaged. A loose or corroded connection can also cause erratic readings and trigger the check engine light.

I used an OBD2 scanner and got a code related to the fuel pressure regulator, but without much detail. Is there a way to bleed the system after a fuel filter change to prevent air bubbles Where is the pressure sensor located so I can check the connections

The error entry after changing the fuel filter is a common thing. Some vehicles have a manual bleed screw, while others self-bleed after a few ignition cycles. Consult your vehicle's service manual for the recommended procedure. The pressure sensor is usually mounted on the fuel rail, near the fuel injectors. Trace the fuel line from the regulator; it should lead you to the rail. Given that you're getting a specific code and experiencing these symptoms, and considering the DIY filter change, it is best to take it to a workshop.

I took it to a workshop and you were right, it was the fuel regulator. The error code was clear once they used their diagnostic tool. Something went wrong during the fuel filter replacement. It cost me 45€ to fix, but the check engine light is gone, the idle is smooth, and the power is back. Thanks for the help