edvc520

Hi, my 06 is250 AWD has this P0420 error code.
I have searched, some body says change the whole header, somebody says change bank1 sensor 2, or a cheap fix by putting a spacer on for the o2 sensor.
Anyone know what should I really do?
Thanks

calvin2376

iTrader: (2)

http://www.obd-codes.com/p0420

Provide some more background - is your car stock? Have you done anything to it, specifically replace headers/exhaust/etc? Any symptoms? Any work done on it recently?

edvc520

it's stock.. haven't done anything to the car..
though the CEL has been on for more than half a year

calvin2376

iTrader: (2)

You've driven with a CEL for over 6 months and haven't gotten it diagnosed? That might be my first step...

Defender46

iTrader: (2)

Needs a cat, so the whole exhaust manifold for bank 1, the left side. I've never heard of an o2 or a/f sensor causing that code, its one of those cut and dry codes-can only be one thing unless its a weird wiring/computer issue.

mahcah

iTrader: (3)

Try a tune up. Replace the spark plugs. Perhaps the fuel is not being burnt all the way thus the ethanol gets deposited into the cat. After the tune up, reset the code. If the light doesn't turn on again after about 100 miles or so, that is the solution to your problem. The new plugs are burning all the ethanol away. If the light comes back on even with the tune up, the cat needs to be replaced. It would be cheaper to replace the plugs first, and then find out if that's the problem or not rather than to straight up replace the cat.

Likwid XTC

iTrader: (5)

I got the same thing change the o2 sensor I just ordered mines. Bank 1 sensor 2. Which I believe is the passenger rear and when checking the o2 my wires were corroded through.

edvc520

Thanks for the response guys..
If i need to change the bank 1 manifold, is that the passenger side?
Where is the best place to find this? I think the dealer will charge me an arm for it
Also, I don't think there's any aftermarket ones for AWD now right?

Denver

iTrader: (13)

dealer parts may be more but will last way longer than autozone, napa, or advance auto parts.

Defender46

iTrader: (2)

bank one is the left, or driver's side. And when it comes to sensors/cats you definitely want oem, might cost a bit more up front, but even with an autozone lifetime warranty or whatever do you want to change it out once a year ?

Tajai7

I was aware of the carbon build up issue so when I started getting a P0420 trouble code to routinely come on after 77k miles (came on 6 times between 77k and 81k miles) on my '06 IS250 AWD (catalyst system efficiency below threshold bank 1), it was time to take it to Lexus and argue that the carbon build up is causing the rough idling and is also damaging the cat, causing the trouble code to pop.... They wouldn't confirm that the cat was under warranty to 80k miles like I've seen in other posts, but They did acknowledge the carbon build up issue and replaced the pistons and decarbonized the cylinder heads, etc. And also replaced the failed cat as a goodwill gesture. I was very satisfied with how the dealership handled this issue, especially because it did not cost me a dime! Apparently the engine is covered under a nine year Lexus warranty. Try to take advantage of the carbon build up TSB and argue that it's damaging the cat, it worked for me.