To clear the code or not clear the code, that is the question
 

My SES light is on. Its the O2 sensor. I know which one so I replaced it today. Do I need to reset the ECU and clear the code so the light goes off or will it go off on its own.

You can reset with your scanner or code teader. Or it will go away on its own.

Are you trying to pass an emissions inspection by the end of the month?

Yes!!! Actually... my inspection is due in 10 days. The last time I reset it with my scanner I drove it about 80 miles and brought it back for testing and it failed because all the systems hadn't reset. They told me to drive around for another 100 or so miles. I can't possibly drive the car close to 200 miles in 10 days. I will be lucky to do 75 miles tops.

clear the code and take it in, don't warm it up. they're going to do that anyway. it should pass.

Nope! You clear the code(ERASE), then you'll need to accumulate about 85 miles for your monitor readiness to clear than take it in to be inspected and you should pass!

My car in 10 miles or so most of the codes are ready. In New York our old cars do not have to have all readies. I think one or two can be not ready.

My car in 10 miles or so most of the codes are ready. In new york are old cars do not have to have all readies. I think one or two can be not ready.

Actually in New York at 25 years old is exempt. Most people don't check dmv website ,4th gens are coming up on exempt.

DO NOT CLEAR THE CODE WITH A SCANNER! When the exhaust shop installed my new cat and O2 sensor they cleared the light without me asking. It then failed inspection multiple times because the system was "not ready". I drove well over 100 miles and it still failed. It was a huge pain because I had no way of telling when to go back again. Finally on around the fourth attempt it passed. Just drive it around until the light goes off by itself and you should be good.

It will clear on its own. Let it do so. Take the car out on the road unsee various driving conditions. The more you drive it, the sooner the light will go away.

Also the rest of the systems will be "ready".

I asked the question about emissions inspection because the systems need a ready status to pass.

Not clearing the code won't delay the Ready state, will it? It just lets you know when it's ready to pass, so you're not guessing? I normally clear things like O2 codes to see if they come back, but if that would delay things I'd be more careful close to smog test time...

Not clearing codes means that all the other items are "ready" for emissions inspection. As soon as the light goes off by its self, all systems are ready for inspection.

Clearing codes means that NO codes are"ready". No new codes does not mean that the car is ready right away. They might need 50 to 100 miles to get to the ready status.

Clear the codes.

There is no mileage equivalent for emissions monitor readiness. Look up the drive cycle and repeat that until you have enough monitors ready.

Most scan tools can check system readiness status - check that before you take the car in for testing. Your state may allow a certain number of 'not ready' monitors.

here in pa they'll give you a waiver sticker after you spend a $100.00 trying to get your car to pass, that way at least you don't have have to go back and fourth trying to get it to pass emissions. i really don't get how some states don't even have inspection while most of us go through this.

So.. here is where I am at. I have put about 200 miles on the car since it failed emissions due to the fact that several of the systems were NOT READY.
I checked the codes with my OBDII scanner and they are STILL not ready.
About 80 miles ago I replaced the upstream O2 sensor because the check engine light is on throwing code P0174.
That light is still on and my scanner is still calling out P0174 so I am hoping I just need to drive it more.

What a pain in the butt. Do I have to result to bringing it to a repair shop? What would they do exactly? P0174 has a bunch of possible causes. Car runs perfect although just a few days ago it decided to stop going into 4th gear (overdrive). The only code present is P0174 and a bunch of systems that are reading NOT READY.

I am getting very frustrated about this. My emissions safety check is already passed due so I will have to pay the fine once its finally repaired. I just don't know what to repair to get this stupid SES light off.

I had similar issues. I eventually changed the fuse. Problem solved.

I think that the corrosion on the fuse caused the code.

did you do the battery terminal reset trick, disconnect the pos and neg and touch them together for i think 2 minutes and reconnect the battery. it supposed to reset the ecu, i tried it and it did nothing, but i wasn't having the same issues.

the oxy sensor fuse. It's located on the rightmost row of fuses in the fuse box by our left knee.

UPDATE.... as of today 1-9-19. Oxy Sensor Fuse is good. SES light is still on. Code P0174 still.
I have driven about 100 miles since i replaced the O2 sensor. I have driven almost 300 miles since I failed emissions. I scanned my ECU and it still shows several systems NOT READY.
I am starting to think that P0174 is not being caused by my Upstream O2 sensor (the first one in line after the front exhaust manifold).
Car runs 100% perfect with no issues other than the SES light being on causing me to FAIL EMISSIONS!!!!
If I have intake or vacuum hose leaks I can't find any and there is no indication that I have them.
At this point I don't know what to check. Incredible. I have owned this car for almost 10 years with no issues at all other than general maintenance. Car has 180,000 miles on it and runs and drives like a new car. I prefer to drive it over my other 2 cars which are a 2013 and a 2015.
I may have to park it for good because I can't get this stupid light to turn off so I can pass emissions.
Any suggestions? Thanks..

My original fuse looked good. But I had the same issue. I replaced it with a new fuse, then the problem went away.

Question..... please describe the driving conditions.

Do you drive the same route all the time?

Do you drive a combination of city and highway?

I replaced it with a new fuse even though the one I removed was perfect. No change. Regarding my driving conditions.... I have taken the car 80 miles on the highway doing 60mph... I have been in stop an go traffic in town for 20 minutes. I have driven around town for at least 100 miles. I have done every type of driving with the exception of drag racing or dirt track with the car. It runs 100% perfect with absolutely no issues at all. Its even pretty decent on gas. YET.. several of the systems still aren't ready and the SES is on showing 1 code. P0174.
Engine idle is so smooth sometimes I think it stalled if it wasn't for the tach.