Hi,

I recently bought a 07 IS350 with a custom stainless steel exhaust. After a couple days of driving - today, the CEL, check VSC and traction control light came on. I got it checked at a mechanic and the code was P0420.

I had a couple questions and would appreciate if someone could help me out.

1. Would I need to replace the catalytic converter? Should I first replace O2 sensors?
2. What would happen if I don't replace the catalytic converter?

Sorry for the newbie question, I'm not super well versed with cars. Thank you for the help in advance.

 

Check for an exhaust leak, especially near the Y-pipe. (sometimes leak is under the heatshield) It's the most common cause of the P0420 and P0430 codes, and especially likely in areas that use a lot of road salt and snow melting chemicals.

 

Okay, I appreciate, I'll look into that!

I was wondering, if I don't change the catalytic converter (i.e. ignore the code), would this be detrimental to the car/engine other than bad emissions?

Thanks again for the help.

 

99% not the cat. Remove the midpipe, remove the heatshield, repair the leak/crack/whatever it might be, seal, you're good to go. If you want to DIY, you need O2 sensor sockets. Go get new exhaust seals in the meantime as well. I wouldn't patch it up with a "patch tape" or anything along the lines - you don't want anything not letting moisture get away from your exhaust pipes. They rust under the heat shields for a reason

The cat is the last thing on Toyota's service manual troubleshooting diagram for cat codes. Exhaust leaks are the primary.

Haven't heard of any cases (of toyota engines, at any rate) of bad cats breaking down and the engine breathing in ceramic dust. Highly doubt that the cat's clogged either - assuming you have normal fuel consumption, no black smoke, no loss of power and no oil consumption (or at least nothing along the lines of 1/1000).

Failed OEM cats are rare. Midpipe leak on the 2IS/3GS is extremely, EXTREMELY common.

 

Thank you so much for the help, I really appreciate it. I'll get it checked out this week. Thanks again.