Could Faulty O2 Sensor Cause Not Ready Emissions Reading

[DAWG NATION]

Hey Guys
Still trying to get Big Bertha to pass emissions. After many many miles and drive cycle still having not ready error from O2 and Catalyst.

Mechanic told me it may be a bad O2 sensor and he suggested I put in a new sensor.
Could he be right?

Thanks

 

[ElectroBoy]

Hey Guys
Still trying to get Big Bertha to pass emissions. After many many miles and drive cycle still having not ready error from O2 and Catalyst.

Mechanic told me it may be a bad O2 sensor and he suggested I put in a new sensor.
Could he be right?

Thanks

You’re probably not meeting all the criteria for a “drive cycle”. Check out some of these threads below. Or Google search for a phrase like: “3rd Gen drive cycle catalyst ready”. There is also a TSB at this one:

Why might the catalytic converter monitor be not ready for CA mog test?

How To Perform a Toyota 4Runner 4.7L Drive Cycle?

I had this problem occasionally on my 3rd Gen also. The drive cycle completion resolved it, but you could need a new sensor. Good luck.

 

[Joelzy]

i ended up with the catalyst code on the way to do emissions, new O2 sensor and about 50 miles(cranks here and there throughout) did it.

 

[JMat]

i ended up with the catalyst code on the way to do emissions, new O2 sensor and about 50 miles(cranks here and there throughout) did it.

A new front O2 sensor did the same for me.

 

[DAWG NATION]

i ended up with the catalyst code on the way to do emissions, new O2 sensor and about 50 miles(cranks here and there throughout) did it.

A new front O2 sensor did the same for me.

So after doing the drive cycle etc. You were still getting O2 Sensor and Catalyst "Not Ready" errors and only replacing the front O2 sensor fixed the problem?

 

[JMat]

So after doing the drive cycle etc. You were still getting O2 Sensor and Catalyst "Not Ready" errors and only replacing the front O2 sensor fixed the problem?

Yes... Using my OBD2 reader I noticed it had said that for at least a year and wondered if it was something that wasn't supported so didn't worry too much. I finally decided to replace my upstream O2 sensor just because it had about 330k miles on it and within 20 minutes of driving it around the Catalyst read"Completed". Seems the Catalyst drive cycle is an pretty easy one unlike the Evap.