My 2024 C8 1LT has 340 miles and the O2 sensor not ready. Are there any ideas as to why and how to get it ready? I need to get ready for registration in CA.

 

Drive it some more, preferably long drives with highway miles. Then take it back and have it checked again. Very common problem.

 

You or someone using a scanner found one or more oxygen sensor(s) has not passed the ready monitor? This is unusual for the mileage you have on the car, but not impossible.

In short, the ready monitors look at the performance of several systems once certain test criteria have been met such as engine speed, coolant temp vehicle speed etc. Once inside the test window, the system’s sensor(s) are monitored and must meet an allowable tolerance for performance. If, In driving your car, you never satisfy conditions to enter the monitor's test environment, this ready monitor stays open. A ready monitor will stay open also if the sensor’s performance does not meet the programmed test requirements.

The O2s are part of the federal emissions system and if your new car is unable to pass an emissions test, I would bring it to a dealership so they can address this. It is possible for an O2 sensor to not be able to pass a ready monitor, yet not set a check engine light. There are other reasons as well that further diagnostic testing would reveal.

You could try driving the car to simulate conditions found in a the drive cycle monitor test. This would be most likely met by holding a steady state 45 to 50 mph for 10 minutes with the engine stabilized at normal operating temp and engine speed between 1500 and 2000 RPM. Switch to manual shifting mode and hold the right gear to give you this engine speed.

Good luck

 

It can take up to 1000 miles for all the emission monitors to set, but in CA you do not need to have the monitors set in order to smog, but you do have to take it to a smog referee who will scan the car and give you a smog certificate for $8. All you need to do is call the smog referee appointment line and make an appointment. It takes about 45 minutes for the whole inspection. I used the referee on my 23 C8 which had 300 miles and I just did my new 24 CT5-V with only 60 miles. Once you have the certificate you can get your registration.

 

Called and scheduled next Monday. Thank you!

 

I have same issue on my '25 with 1200 miles on it. 3rd time being smogged tested for stupid CA reg requirement even though built for CA but took delivery at museum and it is still not open. Any help on this?? I've heard anywhere from 600miles on up to "whenever"

 

Hi, does the smog referee work for you? I called them to schedule a service, but failed. They gave me two options: if I think I have driven a reasonable amount of mileage but the sensor is not ready, I will need to go to either the dealership or the smog repair station instead of the referee program