The Cat. Converter went out on my 2008 Fit. I took it to a dealer who wanted $1500 to replace it - they said they would do a software update to ensure any underlying engine issues would be addressed. Needless to say I got the CC replaced elsewhere for a much lower cost but am wondering about the need to take it to a dealer for this software update. Was the dealership giving me yet another line about something not needed but will cost me money - or should I get a software update?

 

I don't see how a software update would address "underlying engine issues." A software update will not tell you if you have low compression in a cylinder, a misfiring spark plug, a faulty fuel injector, a bad coil pack, or a slow oxygen sensor, all of which could contribute to needing a catalytic converter. A software update may recalibrate the acceptable values for your catalytic converter thereby negating the immediate need for its replacement. However, the dealer was correct in saying that diagnosis of underlying engine issues is important. If not done, whatever caused the original converter to go, may cause the new one to go also. I would particularly pay close attention to both oxygen sensors. The upstream one tells the computer how to alter the mixture to keep the right air/fuel ratio and the downstream one tells you the condition of the catalytic converter, so if one or both of these is marginal, they can affect the converter and also your computer's assessment of the converter. If you put an aftermarket converter in and plan to keep your car, IMHO you made a big mistake. They do not last anywhere near as long as the OEM ones last. Aftermarket converters are not even allowed in California! My advice is to buy a Honda converter from an online source such as Bernardi.com and buy OEM oxygen sensors from RockAuto and then have an independent garage install these for you and diagnose if there is anything else wrong to cause the converter to fail. Since you already have your converter installed, I would check with the people who installed it to see if they looked for what caused the problem in the first place. Ask them if they checked mode 6 data for misfires and for oxygen sensors near their limits. If they do not understand this, then bring the car to someone who does. It may be the difference between a long life or early replacement of your new catalytic converter.