Device placed within the exhaust system used to catalyze pollutant gasses found in exhaust gasses. Is normally located after the exhaust header, but before the muffler. Can be configured as 2-way or a 3-way: the 2-way affecting hydro-carbons (HC) and Carbon-monoxide (CO) gasses; the 3-way affects ...

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11
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4answers
583 views

How can I tell if I have bad cats?

No, not that cat! Catalytic converters - or "cats" - have a nasty habit of failing with age. What are the symptoms associated with a cat that's gone bad? Are there any tests that could ...
11
votes
3answers
68k views

Check Engine code P0420 Catalyst efficiency below threshold bank 1

After months of normal driving with no problems, my 2003 Honda Civic EX check engine light came on during a long trip. Got it scanned and it's P0420: Catalyst efficiency below threshold bank 1. They ...
9
votes
3answers
7k views

Catalysator broken? Odd rope coming out of the exhaust pipe

[UPDATE] SOLVED! Hurray! The muffler had corroded inside and it blocked the exhaust system, making bad to motor. I got it fixed and the car energy efficiency improved from 12-15 liters/100km to ...
7
votes
1answer
68 views

Breaking in a new catlytic converter?

I read somewhere you need to break in a new catalytic converter. To that end: Is this accurate? What is the purpose of breaking one in? How do you break it in?
10
votes
1answer
5k views

What are the tell tale signs of a catalytic converter that might be going bad?

I've owned two vehicles whose catalytic converters were recalled due two a couple of reasons: one being the quality of the CC and the other being a reduction in power due to a material building up and ...
7
votes
1answer
84 views

Locating the O2 sensors and the cat along the exhaust

I gather that the upstream O2 sensor is the one right in the center of this picture. I also gather that the catalytic converter (the "cat") is the bulbous part of the exhaust right behind this sensor. ...
7
votes
3answers
376 views

2003 Toyota Corolla, 185k: erratic OBD codes, fuel smell, other symptoms

TL;DR: O2 sensor data, thermal measurements, and physical resonance tests all point to a failed Catalytic converter. Here's the back story. MIL illuminated with codes P0440, P0420, P0404. Around ...
4
votes
1answer
2k views

How to determine if P0430 is O2 or catalytic converter

2009 CTS4 3.6L P0430 catalyst below efficiency bank 2 comes on periodically. (There are no other codes being thrown.) I put a data logger on it today on my drive to work and the rear sensor is ...