it's usually the cat needs to replace. if it's o2 sensor, it would show bank 1 sensor 1 or bank 1 sensor 2 etc.

 

Most likely your cat might be bad. Swap your o2 sensor from driver side to passenger side to see if it follows. If it doesn't your cat bad if it switches bank your sensor bad then.

 

I was receiving the same VSC, VSC Off, & CE lights on and got the O2 sensors replaced. The lights were still coming on. Then was told my CAT needed to be replaced after getting a code of P0420, and that the O2 sensors mimicking; found out NOX high at idle and cruise. Replaced the CAT and all lights are off and appears to run better. Will be changing the spark plugs soon as well.

Hope this helps, and good luck.

 

lucky if its just one sensor going bad. Ive seen both bank 1 and 2 sensor 1's go bad at the same time lol

 

im running the p0430 for at least a year on and off i still cant figure it out. it would come on and when i turn off and on the car it goes away. it actually stayed for a long time after a 4 hour drive but then it went away by itself, after a few drive cycles like 4-5 days. most people haven't figured a definite answer it seems its on a case by case basis. my code didnt tell me what sensor either. i have noticed my exhaust has been running a bit rich cuz black stuff on the inside of my muffler has been getting thick a lot sooner than it use. im cleaning it more often.

 

Thanks



Yeah the light goes on for a little while and then off for a little while. I have also noticed that lately my right muffler has been putting out more black stuff and the left side is always clean almost like its never on lol.. What do you mean its running a bit rich? How do I change that?





I ran a better computer on it this weekend and its the O2 sensor going back the CAT seems to be fine.

 

higher amounts of gas during combustion.... thats about as simple as i can put it.
how did you check the cat? most people just bang on it and listen to see if stuff rattles.
i havent been under my car to check... ill probably run it on a better obd2 later. i got to much stuff going on otherwise. at the end of the day the code is only a guideline.

 

Yeah just banged and listened both sound the same

 

brought my car to a shop and put it on an OBD2. i ran live tests and couldn't find anything wrong with the signal it did find the freeze frame dtc but all the signals looked good. i guess im going to wait it out. im not trying to replace cats unless im 99 percent sure. i may just take off the sensors and clean em with electronic cleaner then swap em.

 

2006 Gs300: P0420 and CheckEngine shown up along with VSC next day after Ran over the big mountain rock. Got pinched on exhaust pipe 3" next to down stream O2 sensor and leakage between the flange join where Cat and heder bolt together. I bought Ishino exhaust gasket (W0133-1643507-ISH) from Amazon double up with the old gasket to seal the leak, then P0420 came back few weeks later. Replace both sensor b1s1 b1s2 still no luck.
Just replace the midpipe with Megan racing which delete the secondary Cat. Hey. Cel P0420 not show up for 3 weeks now. The o2 sensor wave form reading are nice as same as B2
P042 is bank1 Cat but it can be either main or secondary. Judge yourself before replacing it (oem main front Cat $850 oem midpipe $1450) I'm being cheap to go with Megan midpipe $365 works for me
.

 

not to revive an old thread but i know someone recently mentioned they were getting these codes.

so i might have the problem as well and since my TC light is lit (along with CEL and others), does that mean my TC is off? it has been first snow around here and it felt kinda weird when i slide around having driven with TC on for so many years. why is it OFF when I might have a cat problem and isn't that a safety issue?

 

Yes, traction control is turned off and the resultant "check vsc" warning is displayed whenever the check engine light is on, regardless of what trouble caused it.