گرفتگی یا تنگی مسیر اگزوز

The exhaust obstructed anywhere along its length, so the engine cannot breathe out. A collapsed converter substrate is the usual cause, along with a crushed pipe, a failed baffle in a silencer, or debris from an earlier failure lodged downstream.

The signature is a power loss that worsens with revs — the engine pulls acceptably to low revs and then hits a wall — with airflow and boost readings falling short and the turbocharger unable to work against the backpressure. Measure backpressure directly at an upstream oxygen sensor port; it should stay low as revs rise. Find where the restriction is before replacing anything, since a fragment carried into a rear silencer survives a new converter.