OBD Code P0431 on 06 Mitsubishi Eclipse?

Question

My 2006 Mitsubishi Eclipse is reading the code P0431 (Warm Up Catalyst Efficiency Bank 2 Below Threshold) What exactly does this code mean? I read online that it obviously has to do with the cat, but it also could be due to a bad O2 sensor. The Service Engine Soon light came on, and about a week later went away, then a day after that went back on again. I can heard my exhaust make a rattling/ticking noise around the front of the car, and actually had a friend mention that it might be a cat problem, so I am guessing that is the problem. How long could I go without fixing this until it becomes a problem? It started 2 weeks ago, but I just had a chance today to take a look at it since I've been busy. Just need some clarification, thanks!

Anonymous · Answer

P0431 Mitsubishi

Stpaulguy · Answer

((How long could I go without fixing this until it becomes a problem? ))

Whatdya mean? It's already a problem!

The computer expects to see a slowly changing reading coming from the O2 sensor after the cat. If the cat isn't doing it's job, the reading will fluctuate quickly and computer will set the code. Could be a bad upstream O2 sensor, but could also be a dead cat. Get it checked out sooner rather than later.

Anonymous · Answer

Basically, it means that the computer is "seeing" oxygen downstream of the cat and it shouldn't. The catalytic converter is designed to use up every last bit of oxygen. It is possible, and not all that uncommon for a crack or bad gasket in the exhaust plumbing to cause this code. Make absolutely sure that the exhaust system ahead of the sensor doesn't have any leaks before you replace the cat..

JJ · Answer

The only "problem" will be getting it to pass the inspection. Other than that it doesn't matter AT ALL.

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OBD Code P0431 on 06 Mitsubishi Eclipse?

4 Answers