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Aftermarket catalytic converter for mercury sable does not work

I drive a '97 mercury sable,with 200K, the engine light came on, the garage diagnosed a bad converter, outsourced the installation to a muffler shop, which I found out last minute, installed an aftermarket product, cost about $900, after a couple hundred miles, engine line came on again, diagnosis bad converter, mechanic says the aftermarket converter is not being recognized by the car’s computer, he needs to do a “calibration”, more money, I called around the service departments of ford dealers, same say I need a converter from Ford, others say they never heard of something like a “calibration”, others the chance of a “calibration” to work is not guaranteed. Is there something like a calibration??? Should the mechanic have known better how to fix the car? Who is right? Can I continue to drive without damaging the engine? Is the engine performing with lower gas mileage? Otherwise the car is in good shape and condition.

The aftermarket cat is not as efficient as the factory replacement. In other words, it can’t do the job as well. The car’s computer is required by law to monitor the emissions, and it says the cat is garbage. A ‘calibration’ will change the parameters of the sensor, so the computer thinks the cat is doing the job right. It is iffy, and can result in more codes. I’d get the right cat on there. Aftermarket cats on any car made after 1996 is a sucker bet.

BTW, you are not damaging the engine. The cat’s only job is to clean up the exhaust before it goes out the tail pipe. It will not hurt the engine or gas mileage unless it is more restrictive than the original cat. And, generally, I find that not to be the case. They are just not as efficient as the factory ones, and sometimes do not get the job done.

It’s too easy for many mechanics and shops to just change the catalytic converter when there is an engine code indicating a problem with the catalytic converter system. It’s fast, easy, money. They are, actually, doing you, and, collectively, other Americans, a disservice. It’s not as if there are not troubleshooting charts for them to follow. There are, and they know it. If they don’t, they should get out of the auto repair field.
The original problem with your catalytic converter was caused by the engine. The engine needs tuning, and other repair, and tweaking, to get it to run clean enough for the efficient operation of the catalytic converter.
Check around. You may find a conscientious mechanic / shop who will treat the causes, rather than just the symptoms.

thanks for the 2 comments, in the meantime I tried to get more information
the link below was quite a revelation, concerning catalytic converter regulations, the mechanic and muffler shop failed to give me a warranty for the converter, and failed all the requirements for installers. I think I have a good case.

I’m sure glad I got out of the auto-repair business…An 11 year old car with 200K miles?? You have no case…Your car is not worth the price of a factory exhaust system. Your mechanic needs to learn when to call it a day and stick with brake jobs, water pumps and timing belts…Let the Dealership mechanics deal with CEL problems…

Since I am usually recommending newer cars to a lot of people, I must say that if you can afford to do it, maybe you should consider it. You meet two of my own criteria: The car is a 97 Mercury Sable; it has 200,000 miles on it. The point is that the car isn’t in the mileage range where you can count on it to be economical to own. Repairs can cost a lot and be unsuccessful. For right now, you’re going in the right direction by trying to get a free catalytic converter. For $900, the thing should work. There is also a chance that the part you changed is unable to solve the problem because there is a bad oxygen sensor, fuel injector, or engine control computer. Your best bet at this point is hard to guess. I hope that suggestion number one is possible for you.

I say drop by a local AutoZone, Advance Auto, Checkers, etc. and have them pull the codes. Post the results back here for further discussion. These places will perform this service for you absolutely free and it only takes a few minutes.

Just offhand, sounds like you’re being yanked around a bit. That price for a non-Ford converter sounds awful high to begin with. The fact they’re not standing behind it after such a short time and spouting this calibration nonsense gives me the impression they’re using a brush-off tactic.

for a couple hundred more, you coulda got the cat. from a dealership. If they’re not standing behind their work, you should make sure no one ever visits that shop, even for directions(just like coughjiffylubecough).
Often times a cat. is diagnosed to be bad, but sometimes, it’s really the O2 sensor(s) that need fixed, and replacing the cat. will still cause codes to be shown

thanks for the many more comments -
in the meantime i posted an e-mail to the state epa,division air and radiation, to investigate the car shop and the muffler place. This car shop didn’t tell me till the day I dropped the car of, that they oursource this kind of work. All the time they made me believe the car would be fixed in their shop. I was too stunned to just drive off. The policy of aftermarket catalytic converters by the epa was mainly ignored by this garage, no warranty given, no detail on the exchanged part, no documentation of the replacement- the car has a second engine, and otherwise has been running fine-i did go to Autozone before I went to the mechanic, and a second time, after the new converter had been installed and the engine light came on again, the code that Autozone gave me everytime is P0430,definition: catalyst efficiency low- bank 1, the same that the mechanic told me. I called Ford service departments, the price for the converter I was qouted is around $1400, then you add tax plus labor. I will not go back to this garage but try other venues to recoup my money. I keep you posted.

To Caddyman: the mechanic encouraged me to fix the car, I did mention that the repair is close to what the car might be worth in the Blue Book, considering age and miles.
His reasoning is always it’s still cheaper than paying thousands for a new car. I had no idea that I would end up with this kind of mess.

It still comes back to the question of whether there were any checks done on the cat., the oxygen sensors, engine coolant temperature sensor, etc. These checks can be performed without opening the hood, by using a scan tool with a screen. Any shop has the scan tool…it may be gathering dust, but, they have one (for SHOW, if nothing else). The other sensors’ outputs must be checked before condemning the catalytic converter. Here is a little bit of information on P0420:

Jeepers, $900 sounds like an awful lot for an aftermarket cat! How much was parts vs. labor? You are getting BS from both the shop and the dealers. there is no such thing as calibration for this. There is no reason that the proper aftermarket cat will not work.

I’m also curious as to whether the O2s were replaced or simply swapped over.
O2s are comparatively fragile and are often difficult to remove. Any banging around or severe stress involved in removing them can screw them up.

there was no break-up for parts or labor, just total cost.

new O2 sensors were installed in 2002 $300, tax included.

I did not ask about these other checks, had no idea I should, the mechanic did not offer any other comments other than bad cat. The code is P0430. I use your link and check on P0430.

And, of course, that garage changed the O2 sensors, in 2002, only because there was a check engine light which had the word “oxygen sensor” in its code definition. They, probably, did nothing about the underlying cause for the check engine light. So, now, the same underlying problem has continued to today’s mess.

People need to complain to the appropriate government agencies for consumer affairs, to reduce this kind of fraud…or, any other types of fraud.

There is no calibration that can be done to compensate for a different catalyst. Beware of a mechanic that tells you that there is. Your computer should do a certain amount of self-calibrating, and it takes a half-dozen or so starts for it to decide that something has changed (like seasons have changed, or you have moved to a new altitude, or parts have been replaced) and re-define its acceptable reading ranges. Perhaps the mechanic will just take the car for a few drives around town?

The only data that your computer gets from the catalytic converter is the reading from the rear oxygen sensor, possibly the temperature, and, indirectly, the back-pressure. The car does not directly monitor its own pollutant emissions.

Often, when an OBD 2 computer records a code for a catalytic converter, the actual problem is an oxygen sensor that is getting slow to respond. I have driven my last three cars almost to the 300k mile mark and I have never replaced a catalytic converter.

You cannot determine if an oxygen sensor is getting slow to respond by testing it with a hand-held digital voltmeter. You need an oscilloscope for that test.

OBD 1 cars were less sensitive to old oxygen sensors, but OBD 2s can be quite sensitive. My oldest OBD 2 car has 250k miles and is on its third set of oxygen sensors.

just checked the stubs from the Autozone reading. The first check before the CAT converter was exchanged had code P0420, the second reading after getting the replacment cat had code P0430. What do you make of that?

For $900.00 you should have gotten both catalytic converters as a complete unit that has flanges to bolt directly up to the manifold. I am wondering if only the one bank that was setting off the code had the converter replaced. And now the other side is throwing the code. Pic of a complete unit