chi123

iTrader: (12)

I need opinions on what to do. Just had Autozone scan my CEL and it came up with a P0430 error code. I talked to a Lexus tech and he said my car was running lean and he recommends me to replace my O2 sensor first. However, I searched the code and most say it's the cats failing. The CEL only comes on at certain times though and it randomly stays on and off. So it makes me think that my O2 sensor is not working right rather than my cats not working. It keeps reading 0.2-0.3 even at different RPMs. But since my IS350 has the cats as part of the exhaust manifold, the part is expensive and takes a few hours. I might as well go with headers then if the cats are failing.

mitsuguy

iTrader: (2)

Alright, so, your post kinda doesn't make sense...

First off, how many miles are on your car? If it turns out to be a cat, they have a mandatory warranty of 80k miles and I forget how many years...

Chances are, however, though, that it is just an o2 sensor, if it is stuck at a certain voltage, it should be .4-.5 volts if the cat is functioning properly and being low, would show that the cat is bad, or, the o2 sensor just isn't reading properly... swapping with a known good one (perhaps from the other bank if the connectors fit) - if the code follows the sensor side, then its the sensor, but if the code stays on the same side, its the cat...

If it does end up being a catalytic converter, it is just an efficiency issue - if under warranty, have Lexus replace it free, if not, you can just leave it alone and ignore the light, so long as you don't live where they do emissions testing... replacing with headers would not fix your check engine light, as they would eliminate the cats completely, leaving you in no better shape than you are now

chi123

iTrader: (12)

Yeah, the warranty is 8 years or 80,000 miles. However, my exhaust is modified but I've never messed with the cats. I did delete the secondary cats which are after the the O2 sensors, resonator delete, and a quad exhaust.

But basically my CEL is intermittent and comes on at random times and off. I asked a Lexus tech about the code and he plugged in the Techstream program and ran some Health Check and Bank 2 Sensor 2 kept reading 0.2 to 0.3 while the other one was 0.2 to 0.8 at different RPM.

And thanks for the suggestion. One of the two O2 sensors is working properly so I'll switch them around since they are the same and I guess if an error relating to Bank 1 shows up, then it's the O2 sensor that is bad then.

chi123

iTrader: (12)

Surprisingly, swapped the O2 sensors around and the CEL has not come back on even after traveling almost a thousand miles!

mitsuguy

iTrader: (2)

nice... maybe just some weird combination of cat and o2 sensor efficiency...