Clear Cel for Smog test
Thread Starter
2nd gear
Joined: Sep 2024
Posts: 2
Likes: 0
From: AL
Clear Cel for Smog test
So my RC F has been in storage for months and now that I turn it on for the yearly emissions test, a cel comes up, probably due to the whole nvidia exhaust gasket thing.
I have had it come up before specially during weather season transitions which I am guessing causes the pipes to flex more than normal, creating a micro leak but it normally goes away after a day or 2.
This one however has lasted for several days now and I was hoping to get the test done in the next 2 days before the current reg expires, would an obd2 reader code clear and perhaps 20 mile drive help clear up the code before it comes back? Should I try a new copper rtv layer around before hand again?
I have had it come up before specially during weather season transitions which I am guessing causes the pipes to flex more than normal, creating a micro leak but it normally goes away after a day or 2.
This one however has lasted for several days now and I was hoping to get the test done in the next 2 days before the current reg expires, would an obd2 reader code clear and perhaps 20 mile drive help clear up the code before it comes back? Should I try a new copper rtv layer around before hand again?
Instructor
Joined: Oct 2019
Posts: 839
Likes: 711
From: MD
In general, if you clear the codes then try to go to get smog tested it will fail. This is because clearing codes resets the state of emissions tests in the ECU to "not ready".
If you have an OBD2 scanner, you can check the readiness status of these tests so you don't waste a trip to the emissions inspection station. Since you only have a few days, there is a specific "drive cycle" you can do in order to speed up the readiness checks. I did it once to clear up 'permanent' codes from the same Invidia exhaust leak. Just google search the drive cycle for emissions tests. Tips from memory on the drive cycle: start with less than half a tank of gas; let car cool down for 45-60 minutes so the warm up test isn't starting from full cold; only add 3-4 gallons of gas for the purge test; follow the drive cycle as closely as possible (aka follow the various speeds for the amount of time listed).
I had all emissions tests set to 'ready' and all permanent codes cleared up in about an hour. This was after tests still sitting in a not ready state after 3 days and 200 miles, I'm assuming because it was all highway.
Try the drive cycle first, if the codes come back then do the RTV fix and try again after it dries.
If you have an OBD2 scanner, you can check the readiness status of these tests so you don't waste a trip to the emissions inspection station. Since you only have a few days, there is a specific "drive cycle" you can do in order to speed up the readiness checks. I did it once to clear up 'permanent' codes from the same Invidia exhaust leak. Just google search the drive cycle for emissions tests. Tips from memory on the drive cycle: start with less than half a tank of gas; let car cool down for 45-60 minutes so the warm up test isn't starting from full cold; only add 3-4 gallons of gas for the purge test; follow the drive cycle as closely as possible (aka follow the various speeds for the amount of time listed).
I had all emissions tests set to 'ready' and all permanent codes cleared up in about an hour. This was after tests still sitting in a not ready state after 3 days and 200 miles, I'm assuming because it was all highway.
Try the drive cycle first, if the codes come back then do the RTV fix and try again after it dries.
Last edited by LoSt180; Oct 23, 2025 at 06:12 AM.
Instructor
Joined: May 2007
Posts: 811
Likes: 361
From: CA
So my RC F has been in storage for months and now that I turn it on for the yearly emissions test, a cel comes up, probably due to the whole nvidia exhaust gasket thing.
I have had it come up before specially during weather season transitions which I am guessing causes the pipes to flex more than normal, creating a micro leak but it normally goes away after a day or 2.
This one however has lasted for several days now and I was hoping to get the test done in the next 2 days before the current reg expires, would an obd2 reader code clear and perhaps 20 mile drive help clear up the code before it comes back? Should I try a new copper rtv layer around before hand again?
I have had it come up before specially during weather season transitions which I am guessing causes the pipes to flex more than normal, creating a micro leak but it normally goes away after a day or 2.
This one however has lasted for several days now and I was hoping to get the test done in the next 2 days before the current reg expires, would an obd2 reader code clear and perhaps 20 mile drive help clear up the code before it comes back? Should I try a new copper rtv layer around before hand again?
Thread Starter
2nd gear
Joined: Sep 2024
Posts: 2
Likes: 0
From: AL
In general, if you clear the codes then try to go to get smog tested it will fail. This is because clearing codes resets the state of emissions tests in the ECU to "not ready".
If you have an OBD2 ready, you can check the readiness status of these tests so you don't waste a trip to the emissions inspection station. Since you only have a few days, there is a specific "drive cycle" you can do in order to speed up the readiness checks. I did it once to clear up 'permanent' codes from the same Invidia exhaust leak. Just google search the drive cycle for emissions tests. Tips from memory on the drive cycle: start with less than half a tank of gas; let car cool down for 45-60 minutes so the warm up test isn't starting from full cold; only add 3-4 gallons of gas for the purge test; follow the drive cycle as closely as possible (aka follow the various speeds for the amount of time listed).
I had all emissions tests set to 'ready' and all permanent codes cleared up in about an hour. This was after tests still sitting in a not ready state after 3 days and 200 miles, I'm assuming because it was all highway.
Try the drive cycle first, if the codes come back then do the RTV fix and try again after it dries.
If you have an OBD2 ready, you can check the readiness status of these tests so you don't waste a trip to the emissions inspection station. Since you only have a few days, there is a specific "drive cycle" you can do in order to speed up the readiness checks. I did it once to clear up 'permanent' codes from the same Invidia exhaust leak. Just google search the drive cycle for emissions tests. Tips from memory on the drive cycle: start with less than half a tank of gas; let car cool down for 45-60 minutes so the warm up test isn't starting from full cold; only add 3-4 gallons of gas for the purge test; follow the drive cycle as closely as possible (aka follow the various speeds for the amount of time listed).
I had all emissions tests set to 'ready' and all permanent codes cleared up in about an hour. This was after tests still sitting in a not ready state after 3 days and 200 miles, I'm assuming because it was all highway.
Try the drive cycle first, if the codes come back then do the RTV fix and try again after it dries.
Already had the bad luck of the cel literally coming on the day before I was supposed to take it for emissions so hopefully no more surprises from here on out lol
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