What are the consequences of a blocked exhaust port?

[AlexDella]

It can lead to a decrease in engine power. Below is a related introduction to the automobile exhaust system: Introduction: The automobile exhaust system refers to the system that collects and discharges waste gas, generally composed of the exhaust manifold, exhaust pipe, catalytic converter, exhaust temperature sensor, automobile muffler, and exhaust tailpipe, among others. Function: The automobile exhaust system mainly discharges the waste gas produced by the engine's operation while reducing the pollution and noise of the discharged exhaust. The automobile exhaust system is primarily used in light vehicles, micro vehicles, buses, motorcycles, and other motor vehicles. A car is a comprehensive noise source that includes various types of noise. Since none of the car's noise sources are completely sealed (some are only partially sealed), the noise radiated by the entire vehicle depends on the sound level, characteristics, and interaction of each noise source.

[StArya]

A while ago, the exhaust pipe of our old family car got clogged, causing fuel consumption to skyrocket by 20%. The mechanic explained that a blocked exhaust forces the engine to work harder, like running while holding your breath, requiring more fuel to deliver the same power. The most dangerous part was the high-temperature exhaust gases being trapped—I could feel the rear bumper burning to the touch. Prolonged blockage could lead to engine overheating and cylinder scoring. An emissions test even showed pollutant levels three times above the limit, and the car only passed the annual inspection after repairs. After a heavy rain, we also discovered half a bucket of rusty water accumulated in the muffler, which, when completely blocked, even caused the anti-theft lock to malfunction.

[SanHope]

The worst I've seen while repairing cars is a completely clogged catalytic converter. The owner said the car sounded like an asthma patient, with a puffing noise like flatulence during hard acceleration. The exhaust backpressure reached four times the normal value, and the OBD system directly reported a catalytic efficiency fault code. Upon removal, it was found that shattered honeycomb ceramic debris was blocking the outlet—these fragments had cracked during a previous impact with the undercarriage. Later, the entire exhaust assembly was replaced, and the power immediately returned to smooth operation. A reminder to everyone: don't go over speed bumps too aggressively, as impacts can easily crack the catalytic converter's core, and small fragments can flow with the exhaust gas to clog the downstream pipes.

[DelRachel]

A clogged exhaust pipe can actually trigger a chain reaction. Initially, you'll notice the power becoming sluggish, with RPMs rising painfully slow during full-throttle acceleration. When idling with AC on at a traffic light, the car shakes like a massage chair—this happens because excessive exhaust gas remains in the combustion chamber due to poor evacuation. The most dangerous issue is exhaust fumes leaking into the cabin; a friend of mine nearly passed out from fumes in a tunnel. Modern cars require extra caution—a blocked GPF (Gasoline Particulate Filter) can disable regeneration function, and repairs often cost over 10,000 yuan.