Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Aftermarket catalytic converter for mercury sable does not work

after driving now with the engine light on since beginning of October, the mechanic told me the other day that he “invested in the equipment to flash the vehicle, the system just needs to be flashed. That would fix the engine light problem. The cost of this is $75.00. However, even though it will cost me $75.00, I’m willing to do this for you at no charge…The part is not defective. Your only problem is the computer making the engine light come.”

Has anyone heard the term “flashing” as an automotive term and to fix the engine light problem? I don’t know what to think of that. Before he wanted to fix the engine light problem with “calibration”. I have no idea either what both “applications” will accomplish or if they work for my situation.

The aftermarket cat is not as efficient as the factory replacement. In other words, it can’t do the job as well.

UMM…I hate to tell you this but there isn’t a car manufacturer that makes a catalytic converter. I’ll grant you there may be cheap units out there…but there are some very good ones too…in fact made by the same company that made the OEM one.

Since no one has addressed this yet, you said the first code was P0420. This is for catalyst system efficiency below threshold on bank 1. The new code is now P0430, which is for catalyst system efficiency below threshold on bank 2. So, I’m guessing this is a V6, and now, the other cat is bad and needs to be replaced.

I stand by this statement. Not all aftermarket cats are bad, but there is some real crap out there that are not as efficient as OEM spec. If the code keeps returning, then this cat is crap.

The engine management computers no longer have replaceable chips. They are ‘flash programmable’, meaning the chips can be reprogrammed just by plugging into the diagnostic port. I’m still suspicious, tho. It would seem that he is suggesting to reprogram the computer to ignore the inputs from the rear O2 sensors, or ‘recalibrate’ the computer to accept a lower threshold. I still believe this is illegal, as you are not supposed to modify ANY of the parameters of the emissions system on modern cars. If you have to do a periodic emissions check, this could pop up as a red flag when they plug in.

it is a V6 engine,
as much as I can remember, supposedly the muffler shop replaced the total system, I’m still waiting to get a part number, model number, maker of cat. converter from the mechanic to figure out what they did - the mechanic checked the system after the cat was installed and never mentioned anything that there is another cat which is bad -
the readings I have are from Autozone, the mechanic never put anything in writing- but he insists that nothing is wrong with the cat.converter

Again, someone is jumping to the unsupported conclusion that a trouble code means that a part has to be replaced. This REPAIR BY SYMPTOM technique is plain WRONG!
Ignorance is curable. For your mechanic, download, print, and give to him, this four-page tutorial on P0420/P0430:
The car makers develop and send out software program changes for the engine computer. (Just like you get program updates over the Internet for your pc). These changes “adjust” the programs to have slightly different values. A change may cause the engine computer to, now, allow certain values (from sensors) which it didn’t accept before. The dealer has the computer to flash these changes into the engine computer.
Your mechanic, evidently, now has the scan tool/computer and software to perform a flash update to your car’s engine computer. NOW, if he would just get the alldata, or factory, troubleshooting charts and follow them…

Here is a one-page checklist for your mechanic. Give it to him to follow, and he will, if he’s a half-way conscientious mechanic:

Both converters should be part of an assembly.

Since the vehicle has 200k miles on it, what about the possibiity of an engine peformance problem (no matter what it may be, including any oil burning that may exist) that is causing a problem the converters simply can’t cover?

I’m also in agreement with the skeptics about the computer flash, etc. and there are cheap devices even sold on eBay that are designed to fool the ECM in regards to the O2s and converters.

I just bought a direct fit Walker aftermarket cat for my Chevy for $160.

Plus I sold the old one for $50 to a scrap dealer.

no break-up on the bill, it just states converter for about $ 760, about $50 for diagnosis, plus tax, I asked for a break-up and more details, I’m still waiting for an answer

the engine was replaced at about 125K, I don’t know if that makes a difference in assuming the possibility of an engine performance problem