Catalytic Converter Saga (2001 Corolla Le) - Toyota Corolla, Chevy Prizm (1998-2008)

Guest rthornt

Any help or feedback is greatly appreciated... I'll try to make this loooong story short...

I have a 2001 Corolla LE with 130k miles on it. No major problems until...

10/2007 - Check engine light comes on. Took it to Brake Specialists (possibly mistake number 1?) and they put in an after market cat.

04/2008 - CE light on again. Warrantied out Cat, put in a better one.

06/2009 - CE light on AGAIN. Cat again. Warrantied out. Again.

Both O2 censors have been replaced during this time, too, but I don't recall what months/year... definitely before the most recent cat was installed.

What's in there now is an after market part, but the guy at Brake Specialists swears to me that it should work and that the cat and both o2 censors are working perfectly...

100 miles later, CE light comes on again. I took it to a Toyota dealership today and they're telling me that it will cost $2700 to put in Toyota parts and that the problem is that I have after market parts in (even though according to Brake Specialists, all is working properly).

I'm getting ready to sell it anyway, but I live in a county where a CE light is an auto-fail for emissions. Neighboring county doesn't have these standards... Any advice? Cut my losses and sell the stupid thing for cheap? Is there something anyone knows of that either mechanic could be missing?

Thanks!

Hello and welcome to the forum.

Do you know what the CEL fault code was? Was it always the same code? How does your car run otherwise - fuel economy good, starts and idle OK, any signs of excessive oil consumption?

I'm guessing it is a P0420 "Catalyst System Efficiency Below Threshold (Bank 1)" for them to replace both the O2 sensors and catalytic converter. The issue, is that on the 8th generation Corolla (1998-2002), many that have this code don't have anything to do with either the O2 sensors or catalytic converter. Most of the problem can be traced back to a fault engine coolant temperature sensor and/or leak in the exhaust pipe (crack, or exhaust donut has completely disintegrated).

There has been pretty extensive discussions in the past on this issue - in some cases, it really was a bad catalytic converter and O2 sensors. Given the age and mileage, it is a possibility that those components have failed. But seeing that those codes came back in a relatively short time - I'm pretty sure they missed the primary problem. Just search the forum with your CEL code - should turn up quite a few posts.

Another possible issue is the MAF sensor on your air box, this sensor measures both temperature (IAT sensor) and density of the incoming air via measuring air velocity (hot wire MAF sensor) and temperature from the IAT sensor. This is a non-maintenance part, but many owners that have had a intermittent P0420 or P0171/P0172 "Fuel System Too Lean/Too Rich" - were "fixed" by cleaning the MAF sensor. They make MAF sensor specific aerosol solvent sprays, to help clean up and remove any built up deposits.

Other possible causes, less likely to be culprits - but in concert, could cause other problems that could trigger the OBD codes from earlier. A dirty throttle body, bad injectors, worn sparkplugs or mis-gapped, weak coil on plug igniters, vacuum leak, electrical noise in system, bad ECM.

Guest rthornt

Hello and welcome to the forum.

Do you know what the CEL fault code was? Was it always the same code? How does your car run otherwise - fuel economy good, starts and idle OK, any signs of excessive oil consumption?
I'm guessing it is a P0420 "Catalyst System Efficiency Below Threshold (Bank 1)" for them to replace both the O2 sensors and catalytic converter. The issue, is that on the 8th generation Corolla (1998-2002), many that have this code don't have anything to do with either the O2 sensors or catalytic converter. Most of the problem can be traced back to a fault engine coolant temperature sensor and/or leak in the exhaust pipe (crack, or exhaust donut has completely disintegrated).
There has been pretty extensive discussions in the past on this issue - in some cases, it really was a bad catalytic converter and O2 sensors. Given the age and mileage, it is a possibility that those components have failed. But seeing that those codes came back in a relatively short time - I'm pretty sure they missed the primary problem. Just search the forum with your CEL code - should turn up quite a few posts.
Another possible issue is the MAF sensor on your air box, this sensor measures both temperature (IAT sensor) and density of the incoming air via measuring air velocity (hot wire MAF sensor) and temperature from the IAT sensor. This is a non-maintenance part, but many owners that have had a intermittent P0420 or P0171/P0172 "Fuel System Too Lean/Too Rich" - were "fixed" by cleaning the MAF sensor. They make MAF sensor specific aerosol solvent sprays, to help clean up and remove any built up deposits.
Other possible causes, less likely to be culprits - but in concert, could cause other problems that could trigger the OBD codes from earlier. A dirty throttle body, bad injectors, worn sparkplugs or mis-gapped, weak coil on plug igniters, vacuum leak, electrical noise in system, bad ECM.

Yup - P0420 every time. It's on it's 4th cat, and always the same code. I'll take it back one more time with some of the suggestions you mentioned and anything else I can find on this thread... I'm sold on Toyotas, and I'm hoping to find a good deal on a Rav4 to replace this car - just gotta get the CEL off first! Aside from the engine light, it drives perfectly... and still gets 33-36 mpg.

Thanks!!

kulkarni_ash

I had the same problem for 3 years dealing with P0420 code, there was a mechanic who put in a extra large catalytic converter, This is what he said, this new one looks bigger then the original i had and since then i dont get this light, i dont know what are the specifications of this one, but he cut the pipe and welded the new one, i dont see this for last 1 year...but i see P1349 pop up and go away, and it is very funny when i fill gas at one particular gas station i dont get this code, but when i fill it some where else the code comes back on.

Anyway see if you can find this extra large catalytic converter, i also live where i have to get this inspection done every year and i fix this light just to pass inspection and continue driving,

I think my county has been lobbied by auto mechanics to pass this law, so they can make money every year by forcing people to repair some thing, there is not a single year when i did not had to spend money, every year mechanics pulled some thing from my car to fail the inspection and charge 80-100$ to fix it