I have a permanent code preventing me from getting my 2015 Z06 to pass smog, my check engine light has come on and then off again since the first year of buying car new, dealer told me that there was nothing I could do because the car doesn't have a gas cap, the light hasn't been on for a long time, I only have 27000 miles on my car and even though there are no current issues causing the engine light to come on, it has a permanent code stored, has anyone else had this issue

 

A P0455 is a “Large Leak Detected” in the EVAP system and the dealer if FULL of you know what !!…it can be an actual leak or a faulty EVAP fuel tank pressure sensor or even a faulty vent valve not closing…the EVAP system is also covered under a Federal or California Emissions Warranty depending on which sticker you have on your car…more EVAP parts are covered under California Emissions…I believe the warranty is 8years/80,000 miles but your owners manual should tell you…info below from Alldata for a P0455 for a 2017…read the “note”…the Dealership should have the tool..it is pictured below…they should also have a smoke machine that is needed to find these leaks.

 

Permanent codes are a new thing is 2010 and newer vehicles so folks are not up to speed on them yet. With the check engine light off and a permanent code present does not mean there is anything wrong with your car. It means there WAS something wrong with your car and those codes are going to stay around a while to make sure you fixed it right. If not for a CA SMOG you can basically ignore Permanent codes they are not hurting anyone hanging around inside a ECU.

You cannot clear a permanent code with a scanner or battery disconnect.
You can pass a CA SMOG check with a permanent code in place as long as you have these items in place:
No Check Engine Light (meaning no current codes)
Monitors Complete (Except for EVAP, that can be incomplete)
And this is the important part: Driven 200 miles and have 15 Warm Up cycles since the last time the DTC's codes were cleared.

Now doing this 200/15 task will not clear the Permanent code but rather the CA SMOG machine has been programmed to ignore the Permanent code if 200 / 15 is complete.

Warm up cycles are simply the engine getting up to a normal operating temperature then cooling back down below a certain temp. Below is a video of a guy forcing them on a car with a fan to aid in cooling things down. This can be done in your driveway if you want. The standard for most cars is Up to 160 degrees then it wants to see a 40 degree difference. So cold start up to 160 is 1 warm up cycle. Cool Down to 120 and back up to 160 would be #2. But could vary depending on the car.

Most scanners should have the Data PID's that will show you how many warm up cycles you have done and how long you have driven. If those are better than 200/15 you are good to go for a smog. Look in your "DataStream" or "Live Data" list

One other problem you might run into. If you go for the smog and the inspector turns you away because of a permanent code tell them to kindy run your vehicle through the test. It's not thier job to save you from a fail. They are to run the vehicle as it is presented, that is what the BAR tells them.

If they wont give you a test file a complaint with the State BAR and keep trying another place. I got a guy with 4 complaints in on shops.

https://www.dca.ca.gov/webapps/bar/c...)%20464%2D3405.

 

Have you actually failed a smog test or did they just see the permanent code and send you away?

 

I live in California and did take my car in for SMOG, there was no check engine light and everything went perfectly but the technician was pretty surprised when it didn't pass, he did say that it's an automatic fail if a permanent code exists, I just spent $250 to have the dealership to smoke it and found no leaks, now here's what's really messed up, I need to drive the car to get the code to go away but I can't drive the car because it's not registered, F#$K CALIFORNIA

 

If the dealership smoked it and found no leaks and diagnosed it CORRECTLY they should have done a “service bay test” to see if the EVAP monitor ran and completed… it can be a faulty fuel tank pressure sensor or purge valve and not just a leak…did they check that ??…and if you had no issues with the EVAP system the DTC should have cleared…if you can find someone with a bidirectional scan tool you can do the test in your driveway…I did it once and took less than 5 minutes…for any diagnosis I do whether it’s a Corvette or not I make sure all the monitors are completed…if you don’t see it completed the customer can come back the next day and say their check engine light came back on…you may have other trouble codes pop up when that monitor completes.

 

It's not an automatic fail if they exist. It's a fail if they exist and you have not driven the 200 miles and had 15 warm up cycles.

Way you described it sounded like you had driven it a bunch sine the code went away. Or is this car not your daily driver? Or did you have a recent battery disconnect??
And no you do not have to drive it till the code goes away.

Do you have a scan tool you can lookup the Data PIDs for Warm up Cycles and miles driven since last code clear?
And hopefully the dealership did not clear the codes while it was there and reset everything.