i recently purchased for my wife a used 2003 4-cyl Camry, a/t, 125000 miles, from a toyota dealer. Nice car. After a couple weeks, the check-engine light came on. I got out my Actron OBD II code scanner, which i used to retrieve a P0420 DTC. I researched that DTC on the internet and found out it is a "catalytic converter not performing to spec" issue. I erased the code, and it has not returned in the month since then. I dropped by the toyota dealer to discuss the issue w/ a service tech, who told me that altho i could replace the catalytic converter myself, i would still need to bring it by to them so that they can "recalibrate the computer" after the new catalytic converter has been installed. Back in the 60s and 70s, i had A LOT of experience working on VW Bugs, rebuilding Bug engines, even once rebuilt a VW bug standard transmission. So i like to think i know a little bit about auto mechanics. But back then, VW Bugs did not have catalytic converters, much less onboard computers. So i need to know: on MODERN cars, do you need to recalibrate the onboard computer whenever you replace the catalytic converter? or is this something particular to Toyotas? I have both the Chilton AND the Haynes shop manuals for this car, and neither one of them mentions any such requirement. One further note: I found a TSB for this car on the internet, Toyota TSB EG024-04, relative the onboard computer and P0420 DTCs, but the tech at the dealar told me it does not apply to *my* engine b/c it was built after the Production Change Effective VIN (and that jives w/ what i concluded).

The last time I replaced a catalytic converter was many years ago, as well. I personally have never heard of having to reprogram a computer after such a replacement, especially if you are using an OEM converter. However, just like you. I don't claim to know everything about these newer cars. But there is someone available who does. When you first come to this site, you have an option to "Ask a Toyota Mechanic". There's a small fee for the service, I believe, but it's worth a couple of dollars to get impartial, qualified advice. I'd suggest you do that. On the other hand, you could simply change the converter and just see how the car runs! Good luck and let us know how it turns out. Hy

Thank you. i used the "ask a toyota mechanic" option and had a nice chat w/ a mechanic. he is/was of the opinion that my ECU *does* need to be flashed b/c of the TSB i mentioned; he is of the opinion that the service was NOT done (this is contrary to what the tech at the local dealership told me) . anyway, the P0420 has not returned, so for now i'm just going to watch things. thanks for taking the time to respond

Glad I could help. Have a Happy new Year. Hy