Well, I was hoping that the air filter would fix my problem. It did not. Few days later the P0421 code came back. Tried some catacleaner, it worked. For a day. Next morning, the fault came back. Today I stopped by my local dealer for a "professional diagnostic", hoping that they would tell me something that I don't already know. They did not. I've asked for a PCM reprogramming and they said 190$ diagnostic and the money will go against the PCM reprogramming price which was 190 so 190 total for a diagnostic and a reprogramming. Good deal, i said. I've also asked if I could go and talk to the mechanic myself, hoping that I can see the actual diagnostic or reprogramming and maybe have some questions for the mechanic etc. I was denied. Whatever they did to my car, 40 minutes later my car is out of the shop, I'm going in to pay. The little guy shows me a piece of paper with P0421 code on it and recommends changing the catalytic converter ( of course!). How about the reprogramming? Oh, yeah, we did that, too! Good deal! How much? Nothing, he said. If the light comes back on, you come back and then we'll talk about replacing the catalytic converter... As you probably already guessed, few miles from the dealer, the engine light comes back on, same code. So I'm thinking out loud: these mofos did not do anything, no reprogramming or diagnostic, they just cleared the code and off you go! And that's why I wasn't charged anything! Am I right? One of these days I'm going to crawl under the vehicle and inspect the downstream sensor and take some temperature readings from the converter. I still refuse to accept that the catalytic converter might be bad. This car is only 3 years and a half old.
