صمام التحكم بضغط العادم عالق

The butterfly valve used to raise exhaust backpressure deliberately, seized in position. Restricting the exhaust on purpose sounds wrong and is not — it speeds warm-up, raises exhaust temperature for the aftertreatment, and on some vehicles provides engine braking.

Which way it seizes decides everything. Stuck open, nothing restricts: warm-up is slow, cabin heat is poor, and the particulate filter struggles to reach regeneration temperature — a set of complaints that look unrelated. Stuck closed is a genuine exhaust restriction and produces a severe power loss that reads exactly like a blocked converter.

It lives in the exhaust stream, so carbon on the spindle and corrosion in the bore are what hold it. Disconnect the actuator and check the valve moves freely by hand through its full travel — that single test separates a seized valve from a failed actuator, which produce the same performance code and want completely different repairs.