20024runner

Hello mew here looking for a little help, I’ve been get 420 error code I’ve replace both 02 sensors repaired an exhaust leak and I can’t even get three cold starts with Che k engine light coming back on

 

Error code P0420?

Most 2002s uses an AF sensor and NOT an O2 sensor. Go to your TOYOTA dealer and buy the correct sensors by giving them your VIN. The dealer can tell you which combination of sensors you have by your VIN. No one else can.

If you did replace your sensors with ones from the dealer, the CAT may be bad. Check thermal readings front and back. Back should be hotter if working.

 

Thank you

 

Ok what’s the difference between AF sensor and O2 sensor

 

i found this:

 

Thank you I didn’t know that and once I talked to my mechanic friends a light bulb went off

 

Hello guys changed AF sensors and a week later threw 420 code again I’m pretty frustrated any ideas

 

What did you change? Your AF/airflow sensor goes on the air intake manifold, and your O2 sensor goes along the exhaust system. If you replaced both sensors you could be having vacuum or EGR related issues.

 

I replaced both the Front AF sensor and O2 rear sensor on exhaust no one suggested the are AF sensor

 

Not the MAF sensor, we're talking the AF exhaust sensor.

2001/2002 (depends on the VIN) used different AF sensors instead of the O2 sensors.

-Mike

 

A few things...

#1...did you buy from TOYOTA? Chinese sensors do NOT work for LONG.

#2...did you rule out the catalytic converter? It may be bad. Check the temperature front and back. Make sure the temperature is correct (it should be higher AFTER the Cat Converter)

 

Yes went to Toyota got both front and rear sensors gave vin number to them

 

Sounds like the cat is probably bad then.

Now...there is a cheap thing you can maybe do to get rid of the code:

https://www.youtube.com/watch?v=kzm52m0AWSQ

Worth a try. After doing it, clear the code and pray.

Also, what are your driving habits? These rigs are notorious to throw that code after highway driving. It happens on mine and I clear the code probably once a year.

 

It’s most likely the cat but I don’t have $900 to replace it I’ve heard about the sensor extend I’ll have to give it a try

 

Did you check the before and after temps of the cat? An infrared thermometer is like $20.

You should know where the problem really is.