1999 Mercury Mystique Catalitic converter

VAL BUCHMILLER

MEMBER
1999 MERCURY MYSTIQUE
6 CYL
FWD
AUTOMATIC
99,875 MILES

A mechanic told me one of the three converters is turning on my "check engine" light.
He said one of them is probably going bad, but not to worry until all go bad, because it is expensive to replace just one at a time. Is it ok to run the car like this?
Also, I have noticed my gas mileage had gone down hill.
Would this one bad converter be the problem?

6 Replies

OBXAUTOMEDIC

MECHANIC
3,711 POSTS

Hello,

I would suggest going by your local parts store and ask them to pull codes for you and write them down. Post them here in forum.

If a cat is going bad and is not corrected it can cause engine damage.

Since you have noticed a milage drop the cause can be a bad O2 Sensor or more an exhaust leak causing the O2 sensor/s to read incorrectly or a number of other problems.

So, getting the codes and posting them will help in diagnosing the problem.

.

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Wednesday, March 3rd, 2010 AT 10:48 AM

VAL BUCHMILLER

MEMBER
4 POSTS

I took my car to an O'Reilly auto parts store.
He hooked it up to his machine, and this is what it said

PO430 Catalyst System Efficiency Below Threshold
(Bank 2)

Hoping this will help.

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Thursday, March 4th, 2010 AT 10:53 AM

OBXAUTOMEDIC

MECHANIC
3,711 POSTS

Yes, it does help. So here are other posible cuases for the code.

Bad O2 Sensor or Wiring.

Fuel Pressure to High.

Leak in Exhaust System.

Restriction in Exhaust System (cat or Muffler)

Restrictions in Manifold Vacuum.

Have you noticed any other Drivability Problem? Like No Pickup/power. Hesitation on exceleration.

If Not the posibilities could be either an Exhaust Leak or Bad O2 Sensor or the Wiring.

Check one other thing. In the Fuse Box under the hood look at fuse F13 it is a 20amp fuse.

.

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Friday, March 5th, 2010 AT 8:07 PM

VAL BUCHMILLER

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4 POSTS

Thanks so much for your prompt reply.
I will check the things you suggested.
Hopefully one of those things will make that "Check Engine" light go off.
Hoping also I don't have to change the three Cats. That would be expensive.
If I can find the button to click on, I will send you guys a donation.

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Saturday, March 6th, 2010 AT 9:11 AM

OBXAUTOMEDIC

MECHANIC
3,711 POSTS

You will need to have the engine light turned off. To do that you can go by your local parts store and ask them to do it.

I would start with checking for exhaust leaks, if find any fix them and then have engine codes cleared. Drive it and see if light comes back on. May take a day or two or may come back on shortly after having it turn off. I the leaks weren't the problem.

You will want to do one fix at a time and after each fix have engine codes cleared. Then drive for while to see if light comes back on.

.