A clogged intake manifold is often to blame for this issue, as it restricts proper airflow. This defect stems from the Exhaust Gas Recirculation (EGR) system, which redirects some exhaust back into the intake manifold to reduce harmful emissions. In the process, it introduces dense carbon deposits into the system, according to speedme.ru.

The first sign of trouble is a significant drop in power. The car becomes less responsive during acceleration, struggles to maintain highway cruising speeds, and the engine runs noticeably strained. If the electronic control unit doesn't log any errors but idle speed becomes unstable, it's a clear indication that the intake system needs cleaning.

A second telltale sign is increased fuel consumption. While a clogged intake tract doesn't directly cause higher fuel use, the loss of power forces drivers to press the accelerator harder. For diesel vehicles regularly covering long distances on intercity routes, this leads to noticeable extra costs.

Although manufacturers don't include intake manifold cleaning in scheduled maintenance, experts recommend performing this procedure every 50,000 to 70,000 kilometers. In some cases, buying a new manifold might be more practical, but usually, disassembly and mechanical cleaning suffice. After such treatment, smooth idle returns, acceleration improves, and fuel consumption noticeably drops on familiar routes.