نشتی واشر یا فلنج EGR

The gasket or flange joint where the recirculation pipework meets the manifold, leaking. It carries exhaust gas under pressure, so a leak is an exhaust leak inside the engine bay — noisy, sooty, and admitting air where the system is under vacuum.

The soot marks it. A black deposit radiating from a flange is the definitive sign and is visible without any equipment. The flow effect is what reaches the diagnostics: gas escaping means less recirculation than commanded, so the module reports insufficient flow with a healthy valve and clear passages. These gaskets are single-use and the flanges warp with heat cycling, so a joint disturbed for a valve replacement and reassembled with the old gasket is a common cause — check the flange is flat before blaming the new gasket.