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Can a Cat wear out? 172k on the clock.

ButtonPuncher

Veteran CEG'er
Joined
Aug 15, 2002
Messages
536
Location
Southeast WI
On my MTX, I have a CEL (P0420 I think) saying catalyst inefficiency. The previous owner said that he had just replaced both of the sensors and that didn't fix it. Both of them do look brand new. It's not loosing antifreeze so the O2 sensors shouldn't be screwed up.

The car as 172k on it. Could the cat have worn out?

Thanks,
Ben
 
Bah. I had my batt disconnected overnight this weekend. Reconnected and the car ran better than ever. Yesterday the stupid CEL came on. Now it feels like it has pulled a bunch of timing. :mad:

I've gotta get those MILs. Either the cat is borderline bad or the lower O2 is almost bad.

BP
 
Cats may lose efficiency over time especialy if the gas in the area is off poor quality. Then again 172k is a very long time so i'm not suprised.
 
Does your exhaust smell like rotten eggs?

that may not always be a sign of a failing cat ... they can break down and plug up ...

needless to say, knock on wood, I have 187k on what I believe is the original cat and O2 sensor and I don't have any issues that I am aware of ...
 
Cat failure is more common in vehicles that are driven for continual short hops. Since, in those situations, the vehicle doesn't get up to operating temperature, you're more likely to foul your cats with unburned fuel, etc. If you're a high mileage, highway driver, you may just have happened to reach the point, via whatever factors, where your cat(s) are at the end of their useful life.

For what its worth, my SHO with over 220,000 miles had its original cats, and they were fine. But I did 30K a year, easy.
 
I would say go ahead and stick a MIL eliminator in the downstream sensor, but the real problem is the loss of performance, not the annoying CEL.

Replacing the whole manifold/cat assembly is prohibitively expensive, too.

I think it's time for some headers.
 
Hello! First poster here, nice forum you all run here!

My girlfriend's '97 MystaKe has the same problem. the code shows up fo the catalyctic converter but she had the upper O2 sensor blown out and the car ran fine for a week or so.. then the CEL came back on again.. the car itslef has 130,000 but the enine only has 5000.. this problem has been coming and going for about 2 months now on and off.

does anyone know where to get the sensor for a decent price? I figure we'll try the cheap fix first b4 trying the expensive cat replacemnt.
 
Hello! First poster here, nice forum you all run here!

My girlfriend's '97 MystaKe has the same problem. the code shows up fo the catalyctic converter but she had the upper O2 sensor blown out and the car ran fine for a week or so.. then the CEL came back on again.. the car itslef has 130,000 but the enine only has 5000.. this problem has been coming and going for about 2 months now on and off.

does anyone know where to get the sensor for a decent price? I figure we'll try the cheap fix first b4 trying the expensive cat replacemnt.

You can test the O2 sensors you know. I would suggest Murrays if you can for the O2 sensor. Use a high quality Sensor (Bosch, Motorcraft etc)

Here is a link at the Shotimes FAQ on testing an )2 sensor:
http://www.shotimes.com/php-bin/mod...le=article&mode=thread&order=0&thold=0&sid=87
 
Co 2 sensor

Co 2 sensor

Hello! First poster here, nice forum you all run here!

My girlfriend's '97 MystaKe has the same problem. the code shows up fo the catalyctic converter but she had the upper O2 sensor blown out and the car ran fine for a week or so.. then the CEL came back on again.. the car itslef has 130,000 but the enine only has 5000.. this problem has been coming and going for about 2 months now on and off.

does anyone know where to get the sensor for a decent price? I figure we'll try the cheap fix first b4 trying the expensive cat replacemnt.[/quote

Murray's Auto parts in Cleveland,Ohio has the upper /pre-cat Co2 sensors for $ 58.00 , the down stream is $ 48.00 each
 
Welcome kickaxeguitars. :) .

Your cat converter is gone. Just install a mileliminator ($30 for two, you need one).
 
I finally got my MIL eliminator installed last weekend. I'm still getting a CEL. :blackeye:

I'm guessing that it's still a P0420, but I haven't had time to check the code. I'll also have to try that test above on the sensors.

BP
 
I finally got my MIL eliminator installed last weekend. I'm still getting a CEL. :blackeye:

I'm guessing that it's still a P0420, but I haven't had time to check the code. I'll also have to try that test above on the sensors.

BP
If you installed your mileliminator correctly, you should not have the cat code. Get the code read to be sure. I suspect it is a P0136, O2 sensor circuit. Check your connectors again.
 
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