I just received the dreaded smog check/ OBD scan in the mail today and was wondering how long the ECU stores codes that it has thrown? I occassionally get a P0139 that I clear w/ my code reader and was wondering if the techs will be able to tell that I have cleared my own codes or not. The letter also mentioned that the car will have to run through a few full cycles and they will know if the codes have been recently cleared. Any insite would be helpful

 

sorry just posting to see where this goes. I have read on some of the future regulations coming into effect and what they will be checking. Besides that, here in Indiana it doesn't matter if your car pours agent orange on the road, they aren't checking them yet.... Not saying thats a good thing.

I don't think they look to see if things were cleared now, I think thats what the run cycles are for so if there is an emmision related issue and you cleared the code in the parking lot it will come back on.

There are specific requirements that the manufactures have to meet when it comes to that stuff and how often things have to get checked by the ECU. And they keep changing it and making it more strict.

I would venture to guess as long as it stays off you'll be fine.

 

Don't try resetting the ECU, the readiness checks will show up as FAILED if you do so. It takes the ECU around 500 miles to set the readiness codes as PASS and once it does so, it gathers the sensor's data and the code will show up again. Either fix the problem or somehow find a way to set the readiness codes as PASS WITH the problem you have.