The 02 sensor was deprived from oxygen with all the weed smoke on 420. Sorry, just had to say it.

 

It could be either or both. How many miles on the O2 sensor that is currently installed. The recommended replacement interval is 100,000 mi.

 

... How many miles on the O2 sensor that is currently installed. The recommended replacement interval is 100,000 mi.

And they often are returning a badly incorrect signal by 60-70K.
Not dead, not totally fubar , but no longer reading correctly.

 

I got 150000 miles truck runs great bought it with15k and have only changed thermostat and evap cannister all fluids have been maintained on point and regular maintenance of course

 

My suggestion would be to replace both O2 sensors and see if that fixes the problem. They are both way overdue anyway. ACDelco sensors are probably priced best at rockauto.com or Amazon. The #1, upstream, sensor is ACDelco 213-3207, GM PN 12592592. The #2 (downstream) sensor is ACDelco 213-3139, GM PN 12585999.

Aftermarket sensors are also available at RockAuto and Amazon or at most local parts stores.

Note: Your gas mileage might even improve. The ECM uses the #1 sensor signal to adjust the air/fuel ratio and a deteriorated sensor can affect the signal.

 

My suggestion would be to replace both O2 sensors and see if that fixes the problem. They are both way overdue anyway. ACDelco sensors are probably priced best at rockauto.com or Amazon. The #1, upstream, sensor is ACDelco 213-3207, GM PN 12592592. The #2 (downstream) sensor is ACDelco 213-3139, GM PN 12585999.

Aftermarket sensors are also available at RockAuto and Amazon or at most local parts stores.

thanks brother much appreciated

 

I had the P0420 code for a while. I replaced my downstream O2 sensor 4 weeks ago and the code has not come back.

I bought the Denso for $52 @ Advanced Auto Parts and used their $20 off $50 code. There was a $10 rebate @ AAP at the time. Cheap fix even without the rebate.

 

I have an 06 crew cab I4, with 180k miles. I replaced both O2 sensors when this code came up a couple weeks ago, and that didn't clear it. I ended up replacing the 2nd cat which cleared the code.

 

I replaced my second cat about a year ago thats why im skeptical about the cat being the issue i finally had my dash clear of lights f**k

 

Is the acdelco the best part for a replacement O2? Or is there a better one out there?

 

Bosch makes a good one