Can a Catalytic Converter Clog up Without Codes?

[Donald]

I have a 2001 Mazda Tribute (AKA Ford Escape) V6 3.0 that may have a clogged cat, but I do not have any codes. Is this possible? The symptoms are present on a cold start, but go away after a short drive. The car is sluggish and loud (exhaust manifold leak due to high backpressure?) during the warm-up. I have posted plots of the O2 sensor from my scan tool. This data says the cat on bank 1 is not functioning, yet no code is thrown. Any comments?

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[college man]

It is possible to clog the cat and not throw a code.
If you feel the cat is clogged. remove the bank 1 o2
sensor and see if the power is restored.

[Bill]

Cat’s plug all the time without setting a fault code. I have seen it many times and yet at other times it will set a code for cat efficiency when it is only slightly weak.I have also seen a plugged converter cause a Mass Airflow Sensor fault code.

On that particular vehicle the rear cat tends to be a problem and the manifold warps and bolts break and they melt the EGR valve. (Ford Escape)

That said,a plugged converter usually causes low power when the engine is warm rather than cold in my experience but not always.

I just had an Escape a few weeks ago with a low power complaint and after hours of diag i didn’t come up with anything concreate. The customer decided to drive it for a few more days to see what developed. We havn’t heard from him since.

You could remove the O2 sensor and drive it to see if there is an improvement in power or use a backpressure gauge if you have access to one.

[Author]

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