New Member; first post.

On four or five separate occasions, the Check Engine light has come
on while driving in the rain. The light does not come on at all times
when driving in the rain. Inevitably, when the rain stops and I have
driven about 100 miles, the light goes out.

Lexus dealer said the code reading was PO 430, low efficiency
catalytic converter. I do not think it is Cat because it only
happens when it rains. If the Cat is bad, it is bad all the time,
not just an occasional rain storm.

I believe it may be a faulty O2 sensor. How do I check to determine?
Any other thoughts?

Thanks.

 

First what kind of car is it? Next is you can get a rubber mallet and lightly tape on the cat to see if it rattles. Does the car smells like rotten eggs? If it is none of the above, I would ask you are you actually been using Premium gas 91? Do not use Arco.

 

Welcome to the club!
what car do u drive???

 

I am new to the club and sorry about not listing car. The car is a 2000 GS 400
Platinum Edition with 137,000 miles. I have owned since day one. I always
burn High Test; never have burned regular. Whenever this happens, I am always away
from home in Maine, usually New York or New Jersey. The performance of th car is
never effected by the light going on; there are no strange smells or anything. Just the
light comes on in the rain and when all dries out, the light goes out. Any help appreciated.

ap

 

If you said it only happens when it rains, I wouldn't be too worried. Since it goes off anyhow.

 

I guess my question is whether it is worth replacing the oxygen sensors that
measure the Cat converters' operation on the theory that the O2 sensors
are providing incorrect information because wet conditions have interfered
with the O2 sensors function?

Thanks

 

I would say you should find someone with a scanner than can read live data to check them 02 sensors.

 

Thanks for the suggestion and I will find someone who can read the sensors.

 

Also, be advised just because a CEL goes off does not mean the problem is fixed. The problem is still there hidden in the ECU codes log. My car was acting funky like this. I said the hell with it and bought all new oem O2 sensors. Probably overkill but I know it is at it's most efficient state and code free now. GL!

 

im sorry but that is awful advice. obviously something (something being water) is getting on something it shouldn't which means you have a leak someplace.
the reason it goes off again is cause it dries back out again....sooner or later that constant water source will ruin whatever it is that it keeps getting wet

 

interesting. I have had this go off in my car being slightly newer and it also goes away mine hasn't been related to rain and its the same code that I got. I think it happened twice in the 8 mos I have had the car and it went away. I was told the OEM cats are probably going I also was going to have them replace the o2 sensors assuming they may have gone bad.

 

One other thing I need to add in to make the whole thing appear even more bizarre. The
light does not always come on when it rains. I drove the car a few days ago for a total
of about 4.5 hours on the highway, mostly in sheats and sheats of rain and the light
never came on. And this was three days after the light first came on and two days
after the light went out.

Just can't figure it out though the one constant is that the light never comes on when
it is not raining and sometimes, rarely, comes on in the rain. Go figure.

 

I wouldn't worry too much because it's a Type B code. A Type B code is when the computer doesn't detects it the second time, the CEL will go off. I would just disregard it if you can. What you can do is always put premium gas like Chevron never Arco. And you can replace the post oxygen sensors and that may conclude this problem. GL.

 

Thanks. Will get post Cat O2 sensors checked and possibly replaced and let you
know if this happens again. Here in New England, very little Chevron or Arco gas.
Usually burn Shell or Exxon premium. 93 no longer available in Maine, only 91. So
I try to fill up out of state with 93.

Thanks again; be back in a few weeks with any results. ap