Catalyst not ready issue

[franksbanks]

In Arizona- just got her about two weeks ago, have put 1,000 miles on it both highway and city driving between phoenix and California along driving it back to phoenix form Las Vegas when I got it.

Anyway, I failed smog because the catalyst was “not ready”

anyone else have this issue?
2021 Yukon denali 6.2 l87 10speed

 

[2024 White Tahoe]

In Arizona- just got her about two weeks ago, have put 1,000 miles on it both highway and city driving between phoenix and California along driving it back to phoenix form Las Vegas when I got it.

Anyway, I failed smog because the catalyst was “not ready”

anyone else have this issue?
2021 Yukon denali 6.2 l87 10speed

I haven’t had the issue.

The catalytic converters may be covered under your GM emission’s warranty, which covers certain parts for 8 years or 80,000 miles (no deductible).

 

[franksbanks]

I started looking into that because I have that coverage reflecting as eligible on the myGMC app. It’s weird because the app says my emissions (evaporation and exhaust) are “Good to go. No issues detected “

 

[Fless]

Are you doing an intentional drive cycle like the one at the link below?

GM General Motors OBD Driving Cycle

 

[franksbanks]

I had read up on that just yesterday but had never heard of it. Was more surprised that I had already put 1,000 miles and it was still not ready.

 

[jfoj]

Catalyst Monitor is actually a pretty quick Monitor change to the Ready state. Evap tends to be the most difficult.

Given it appears you purchased the vehicle used, there may be some hidden problem??

How many miles on the vehicle at this point?

I would not be looking at Catalytic Converters as the problem yet unless someone had done something foolish to poison them.

You need to purchase your own OBDII App and interface. This way you can force a reset of the system Readiness, check codes and even look at the O2 sensor behaviors.

The OBDFusion App is available for both Android and iProducts, last I checked it was only $10. Then get VeePeak BLE Interface from Amazon for around $32 - https://www.amazon.com/Veepeak-OBDCheck-Bluetooth-Diagnostic-Supports/dp/B073XKQQQW/ref=sr_1_1_pp?crid=N5NI7QVKZWFZ&dib=eyJ2IjoiMSJ9.aNpakUcyJbfKXQor4XWL6XByQQ_18ByfFZWf2csfPznx97YUFJc1HReF6fxWpkqfJMrjykdSFvdoG-D_IwzRkRAeYfNdI8FGfQB1lZvD25cxBkW9fa6iz4x6ZO3-EKyWRn0CtcuZL1tVOnkUb3EgOMJvO4bjJS3jQm-91-QV9bgYOle6LzuVaR_BNBIJGr3zZ17AJIEd4LdDOmyzuBEJNYOXvIZlJYu7qPpyfpNUjMchL2lqd0XwJ9HX8A6I77ZdgcJsturijSDNq_WpSgLz4MT21BVifEHqBGd3sg10txc.HqpZj8kgdRt5hz6Ebntq-u2_fE3gP3J3jE2JxxoCqTA&dib_tag=se&keywords=veepeak+obdcheck+ble&qid=1785377739&sprefix=veepeak+o,aps,283&sr=8-1.

Keep in mind that you may need to forget the Infotainment system on the vehicle so there is not a conflict trying to connect your phone or tablet to the VeePeak interface. But if you have a tablet, install the App on the tablet and you should not have a conflict with the Infotainment system.


Often you can get lazy O2 sensors that do not cause a code to be trigger, but they are lazy/aged and need replacement. But there could be a wiring issue as well where a sensor has been replaced with a "Universal" sensor that required wires to be spliced. O2 sensor are polarity sensitive on the sensor side, but not the heater side. Wire an O2 sensor output wires backwards and you will have all sorts of strange problems.

 

[franksbanks]

Thanks I’ll look into that scanning app and port connection.
It’s got 71k - I may may just take a trip to my local gmc for a diagnosis scan

 

[jfoj]

The App and interface will cost you under $50, driving in the dealer parking lot will cost you at least double that! Do not go to the dealer for a Diagnostic Scan you will be out probably close to $250 and this doesn't include any repairs

 

[lost1wing]

It being a 2021 also leaves the possibility that your battery is getting weak. It is possible that occasionally when starting the vehicle, the voltage drops enough to cause the emissions readiness to drop out.

Once you get a scan tool that can see the catalyst monitors, you will be able to rule this out or confirm.