Hello everyone,
So two days ago while driving home in the heavy rain from the gym my IS decided to light up the dashboard like a christmas tree. I got the Check VSC, Check Engine , and Traction Control Off light on my HUD. I thought it was the rain or tire slip so I reset the light (disconnected the battery to reset the ECU) and then yesterday same thing again. Decided to take it to AutoZone and hook up a code reader to it and this is the code that popped up.

P0420
Catalyst System Efficiency Below Threshold Bank 1

Of course the employee there didnt know crap about what that ment for me.

Now after some googling I came across a few post saying it was my O2 sensor.


If someone on here could clearify for me what exactly this code means and if it is my O2 sensor where can I purchase new ones ( I know RWD IS350 has two sensors) and if it user friendly to install that would be helpful.


Thanks

 

you have a total of four sensors:
Bank 1 sensor 1
Bank 1 sensor 2
Bank 2 sensor 1
Bank 2 sensor 2

Most likely its Bank 1 Sensor 1.

 

Ok so what does that mean?

 

Your o2 is going out.

I'd clear the code again...

 

Ok clear it and let it pop up again?

 

just hope it doesn't pop up. O2 sensors are pricey.

what scanner did you used to check your code with?

 

I can exactly some orange one Actron AutoScanner Plus

 

Try using another scanner. usually it tells you if its bank 1 sensor 1 or bank 1 sensor 2

 

More often than not it'll be the first one downstream in the exhaust.

Helpful tip, only purchase the OE replacement Denso/NGK O2 sensors. Don't waste your $$ on Bosch or other crap.

 

It's the passenger side catalytic converter that is going bad. I had a P0430 code a while back which means my driver side cat was bad basically. P0430 is the driver side and P0420 is the passenger side. One thing you can do is swap around the O2 sensors on the midpipe. You know that one could be bad but one is still working. If after swapping them around, you still get a P0420 code, then for sure your cat is bad. Otherwise, if the code changes, then it's the O2 sensor. The sensors are on the midpipe under the front two seats.

 

Update: So after resetting the code a few days later it came back on and went away. For the past week this has been happening mid drive CEL, Check VSC, Traction Control lights come on and then maybe a day or two later they go away ( usually in the morning after letting the car sit overnight). Im thinking it might be just the O2 sensor going bad maybe or could it be something else? If it would be the cat convertor wouldnt the lights stay on all the time?

 

Did you purchase a new cat? Warranty? If you dont mind me asking how much was it? Ill do the swap around tonight and see what comes up.

 

HOW YOU GOING TO cREDIT GOOGLE...WHEN I GAVE YOU THE ANSWER....SO RUDE

 

Dont cry Ryan I got your opinion first google was my 2nd opinion I rather double check then check once and be wrong not saying you were wrong

 

haha. doesn't hurt to double check