Hi All
I am a new poster, but have been following for awhile. I bought a 2000 4runner ltd a few months back and started getting the engine light after puddles or rain. The code is 420. I brought it to a shop they say I need new cats, but gave me no specifics. I was betting on the upstream sensor. It being a Bosch installed 2 years ago by the former owner. Call me crazy, but I am also questioning my spectra high flow filter. The truck has 120,000 on it and runs well. The exhaust smell is a little rich I think. Any thoughts?

 

It might be possible your getting water and dirt into the plug even though the Toyota plugs are pretty water tight.

After you clear the 420 Code does the Cel light come on as soon as the test has run or does it stay off till the next major rain storm??

i was showing the same codes so I bought the two cats and senors but was so busy with work I did not have time to change it all out.

The code has not come back since late August.

Go Figure:wabbit2:

 

i understand OEM denso sensors work better than bosch or any other brand in toyota's.

 

this. clean plug assembly with contact cleaner, goop in dielectric grease, see how it goes

 

I cleaned and applied dielectric grease to the sensors. Now light does not come on specifically with rain or puddles. it now comes on and off randomly maybe not as much ad it used too. What seems strange to me is it turns itself off on its own. I am leaning towards replacing that upstream Bosch sensor.

 

While it is possible for the upstream sensor to contribute to a P0420, it is rare that it does so without setting any other code. The rear sensor's only job is to throw the P0420, and would be my first suspect in this case. The fact that it turns off suggests a wiring/connection problem. Connections can heal themselves, at least temporarily. Dead sensors stay dead.

Getting rid of the Bosch upstream might be a good move regardless, however.

 

I had a Toyota only mechanic here in town tell me they don't like Bosch o2 sensors for some reason. my2cents

 

Try cleaning the Bosch sensor with throttle body or MAF cleaner (NOT brake clean or gas) and see if that helps. If not, get a Denso factory one. Rock auto has about the best price around.

 

Judging by the title, I thought for sure this thread was gonna be about a "bong mod." LOL.

 

yeah and i was disappointed

 

me too. I was hoping to see a 4runner bong!

 

Me too lol