What is the issue with the Jaguar XF exhaust valve malfunction?

[MacSienna]

If the Exhaust Gas Recirculation (EGR) valve does not close tightly, some exhaust gas will enter the engine intake pipe through the EGR valve when the engine is idling. Reduction in air-fuel mixture: Since the amount of air-fuel mixture is minimal during engine idling, the exhaust gas entering the intake pipe dilutes the concentration of the mixture, significantly affecting the engine's idle operation. This can cause the engine to idle very unstably or even stall. Exhaust Gas Recirculation: Symptoms of EGR valve malfunction. In many engines, the EGR system routes exhaust gas from one cylinder's exhaust manifold to the EGR valve. For example, in a 4-cylinder inline engine, the EGR pipe is typically connected to the exhaust manifold of the first or fourth cylinder.