[Lightfoot]

My sister just moved to Ohio, and will be needing to get a different car at some point. My other sister is willing to gift her her current (furlough) car when she returns to South America to her regular employment.
Last year when I was getting the car in question ready to register in Maine, I replaced the secondary O2 sensor (per OBD code). Within 5 miles, after the job was complete, the SEL came back on. The only code that showed up was for the same O2 sensor . Tried clearing it out a couple times and even disconnecting the battery for an hour.... Light still came back after a few miles.
Because we have no emission testing in our county, I gave up on it. It delivered excellent mpg on our road trip to the midwest. Exhaust has never been smelly.
17,000 miles later and the engine still runs fine. It's an '03 Hyundai. 97K miles.

Here's the question:
My sister's son-in-law reported that the 'emissions police' have equipment that can detect when a vehicle's trouble codes have been cleared within X-number of miles or days (I forget which; maybe its only hours) and they will not pass inspection if emissions codes have been (are) present.
I was not aware such software was intagrated into a car's ECM. Maybe this is only in the last 5-10 model years?

Anyway, maybe a case could be made that the O2 sensor is 'new' and the damn computer won't let go of the code. I can try clearing it out with the scanner again, maybe after 9 months it will finally 'go away'.

Anyone have more knowledge of this subject?
Maybe Kalifornia residents are familiar with this?

[dataway]

I'd guess the new O2 sensor has a problem. Was it a quality Bosch product or something similar ... there are a lot of discount Chinese sensors on the market.

ECMs hold a provisional code showing they have been cleared within a certain criteria and most inspection stations will not give the car an OK unless that criteria is met.

Same deal in NY.

[tigergto]

After a CEL has been cleared, you have to drive a certain number of miles and through various drive cycles to reset all the monitors . Usually a mechanic will say drive 75 - 100 miles then bring it back. State Inspection Computer equipment can tell if a monitor or monitors haven’t reset. Just because the O2 sensor showed up in the code doesn’t necessarily mean it’s the sensor itself. There are test that u can run to pinpoint the problem. Maybe someone on here can give you info on what those test are.

[dataway]

Could be in the wiring harness to the sensor also. A good scanner can show you why it's throwing the code ... response time, wiring etc.

[rwfisher]

We are now in the same boat here in Vermont. Any CEL tripped within a certain prior period is reason for refusal to pass. So, even if you have an issue and corrected it you won't pass inspection immediately yet you'll probably be in violation of being past your inspection period.. They get you one way or another....

Funny thing is, the country you get most of your replacement parts from to correct your miniscule emission issue exposes the rest of the world to some of the worst emission standards / conformance of any country.. Go figure.....

[salem1912]

If your MIL is on it will fail,if you clear the code (mil out) it will still fail till all system monitors run and pass. This gets tricky some monitor will run in a few miles but some will take several drive cycles(evap system). Most cars have about 4-5 systems that are monitored.Here in Pa cars with mil lite out are allowed one monitor not run(2000 and earlier two). This prevents people from just clearing the codes and going for a emission inspection. Also you can have a "stored"code and as long as the mil lite is off and monitors run it would pass. What p code did you have? FYI a battery disconnect will blow out all monitors so don't clean your battery terminals be for you go for inspection.

[dataway]

If the new sensor failed immediately it is almost positively the wiring or the new sensor is bad. Considering what a pain they are to replace I always buy the best one I can find short of an OEM unit.

[69 Limelight]

How do you determine "best part/piece short of OEM"? I see a lot of people make this statement so do you go on price alone? Higher the price better the part? Warranty? sometimes their the same.

[67drake]

One of my friends owns a shop and told me he won’t use Bosch sensors anymore. He said he has more problems with them than the off brands.Go figure

[salem1912]

A quick mention most cars V6 have 4 o2 sensors 4cylinder 2 are you sure the correct one was replaced? Would need to know the p-code.

[Lightfoot]

Thanks for the replies.
I connected my scanner to try clearing the code(s) one more time. I had not done this since last September, mind you.
Well, it turns out to have a few additional codes in it now. I'll list them.

P0136 O2 circuit (Bank 1 Sensor 2)
P0140 O2 Circuit No Activity Detected (Bank 1 Sensor 2)
P1140 The DTC Definition is not available, please visit www.innova.com
P0036 HO2S Heater Control Circuit (Bank 1 Sensor 2)
P0441 Evaporative Emission System Incorrect Purge Flow

All codes generic except the middle one. So I'm suspicious now that "Bank 1, Sensor 2" might not be a sure way to identify which sensor was tripping the code. Especially when I see "Bank 1, Sensor 2" on the Heater Control Circuit. Anyone know what that's about?

WTH does "No Activity Detected" mean? The sensor is completely dead, vs taking a reading at an abnormally slow interval?

The P1140 is a Hyundai code, that I haven't looked up.
I had the charcoal cannister down and shook a few pellets out of the tube when my dad complained that the gas pump would keep shutting off way before it was full. This was in 2015 when he first got the car. It never turned the light on back then and gas pumping problems ceased. Never saw that code up until now. My sister didn't mention that she was having any trouble pumping gas. I'll have to ask her by email. She's back in Peru now.

[dataway]

Originally Posted by 69 Limelight

How do you determine "best part/piece short of OEM"? I see a lot of people make this statement so do you go on price alone? Higher the price better the part? Warranty? sometimes their the same.

I do my research. Look at the different brands, the reviews on the products, consider where they are made, what price they sell for, who makes the OEM part if possible and price. Warranty I usually don't consider as that is more a business/marketing decision rather than based on quality. Sometimes a higher quality part will give a shorter more realistic warranty than a cheap part that will probably never honor the warranty anyway.

[salem1912]

What size engine? 4 v6?bank 1 would be odd side (#1 cylinder side) and senor 2 would be rear(downstream).. Funny thing about o2 codes, that doesn't automatically mean it has a bad senor. The key word is o2 circuit Check for bad wiring and some cars have a 02 senor heater fuse. The rear sensor can lay up against a hot exhaust and short out might check the harness from the sensor back.

[Lightfoot]

It's a 4 cyl, so I changed the sensor that's underneath on the firewall side. I believe the other one is below the manifold on the radiator side.
No damage to the pigtail. I'm not sure how far into the main harness I can get at to check.
There was a bit of mouse activity in the engine over the previous two winters. They chewed through a place in the paperboard sound deadener over by the master cylinder. And there was a trace of foul odor like one might have died inside the heater box or something.

Does code P0036 have anything to do with emissions? The HO2S is confusing.

[tigergto]

Both codes are related to your 02 sensors, and both have to do with emissions. You may already be aware of this but you can google the codes and it will give you an explanation of the codes.

[dataway]

P0036 is a failure of the O2 sensor wiring, fuse or heater.

Yep ... quick and easy to google the codes, you'll get all the info you need.