# Clearing code to pass emissions



## cfdeng7

I have a 1995 F-350 with the 460 gasser in it. It has an exhaust leak that is throwing the check engine light on via the O2 sensor in the exhaust. I am selling the truck soon and do not want to spend money on a new exhaust (it needs it its like swiss cheese). I have a OB1 code reader but it does not have the clear function. I would like to just clear the 02 bank 2 code to pass emmissions however can not find an affordable scanner. I also have thought about taking the light bulb out from behind the check engine light. Any ideas or links to somewhere where i can buy a relatively cheap OB1 scanner would be greatly appreciated. 

Thanks alot guys.


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## GreatWhiteNorth

disconnect battery and then reconnect. Code will just reappear though once all sensors have reported. I believe o2 sensors must reach a certain temp to function.


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## jb1390

Drive it right down the road from the emissions place, stop and disconnect the battery for 30 seconds, then get the emissions done. If you are lucky, it will take long enough to throw the code that you will be on your way home. OBD1 all you have to do is disconnect the battery or take the fuse out for the ecm to reset the codes.


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## cfdeng7

I assume you cannot shut the truck off after clearign the code? So when I get to the garage and go inside should I let the truck run? and yes the check engine light will not come on untill about 5 min after the engine is at normal opperating temp.


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## CGM Inc.

You still have a warning for 80 miles or so that a code has been triggered. You wont pass emissions with the warning light on. My code reader gives a "orange" emission status after I cleared a code and tells you won't pass emissions. After driving for 120 Km's it changes to green if no codes get triggered.


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## glfredrick

I'd say that the only way to really clear that code is with a decent scanner. Find someone with a Snap On unit. They'll handle the job. Most mechanics have something along those lines, and even an Autozone store may be able to handle clearing the code for free with their scanner.

I'm not sure about how long to reset the code -- you know that better than me on your truck.

Oh, and pulling the bulb won't help when they hook up the computer...


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## sparky8370

You not only have to free of codes, but the system readiness tests must pass. After you have driven around enough, so that the computer is satisfied that all the conditions have been met, and no codes have been thrown you will pass the test. That is why with cedargrounds scanner, it doesn't get green until he has driven around.


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## CGM Inc.

sparky8370;765053 said:


> You not only have to free of codes, but the system readiness tests must pass. After you have driven around enough, so that the computer is satisfied that all the conditions have been met, and no codes have been thrown you will pass the test. That is why with cedargrounds scanner, it doesn't get green until he has driven around.


Thats it! xysport


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## ppkgmsy

sparky8370;765053 said:


> You not only have to free of codes, but the system readiness tests must pass. After you have driven around enough, so that the computer is satisfied that all the conditions have been met, and no codes have been thrown you will pass the test. That is why with cedargrounds scanner, it doesn't get green until he has driven around.


I believe the system readiness requirements vary from State to State. Subarus, practically the State car here in VT, are notorious for having bad O2 sensors and, even worse, catalytic converters, which can cost several hundred bucks to replace. We clear the codes with our scanners and then drive right over to have the car inspected. It will still pass inspection without the readiness being clear.

Having said that, if I was to sell a car to someone after clearing the codes, not sure my conscience would be clear knowing the check engine light will be back on within a week or two.


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## glfredrick

Just replace the parts... They don't HAVE to cost hundreds.

There are all sorts of universal cats for sale on eBay that work just fine. Typical cost is under $50. I've used them and they pass VET. O2 sensors are the same. All it takes is a special socket that costs about $15 and a $35 sensor. Go under the truck, screw in a new one and be finished with the problem. These things don't take a dealer to fix.


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## mustangEd

If you don't want to fix the root cause of the problem,
check summit or jegs for a MIL Eliminator.
it plugs in at the o2 sensor and tells the computer that
everything is ok and will not throw a code or light.
these will not pass a visual inspection.

Ed


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## mayhem

cfdeng7;764963 said:


> I have a 1995 F-350 with the 460 gasser in it. It has an exhaust leak that is throwing the check engine light on via the O2 sensor in the exhaust. I am selling the truck soon and do not want to spend money on a new exhaust (it needs it its like swiss cheese). I have a OB1 code reader but it does not have the clear function. I would like to just clear the 02 bank 2 code to pass emmissions however can not find an affordable scanner. I also have thought about taking the light bulb out from behind the check engine light. Any ideas or links to somewhere where i can buy a relatively cheap OB1 scanner would be greatly appreciated.
> 
> Thanks alot guys.


This is really unethical. You're trying to fence damaged goods that cannot legally be driven on the road as fully operational? Shame on you. Do the right thing, fix the problems before you sell the truck or do full disclosure to the buyer that he's going to need to replace the exhaust and some sensors.

You can repair most exhaust leaks pretty inexpensively, unless it on all the joints. I was able to wrap an exhaust leask with a high temp wrap that went on like a plaster cast and then cured with the heat of the exhaust into some sort of an epoxy. Stuff was still there when the rest of the car rotted away.


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## sparky8370

mayhem;765315 said:


> This is really unethical. You're trying to fence damaged goods that cannot legally be driven on the road as fully operational? Shame on you. Do the right thing, fix the problems before you sell the truck or do full disclosure to the buyer that he's going to need to replace the exhaust and some sensors.
> 
> You can repair most exhaust leaks pretty inexpensively, unless it on all the joints. I was able to wrap an exhaust leask with a high temp wrap that went on like a plaster cast and then cured with the heat of the exhaust into some sort of an epoxy. Stuff was still there when the rest of the car rotted away.


I think you misunderstood, or at least understood it differently than I did. 
My interpatation was that he needs to pass inspection so he can continue to drive his truck. And since he will be selling it shortly, he doesn't want to dump any money into it.
I don't think his intent here is to pull the wool over the eyes of someone interested in purchasing his vehicle.


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## tim096

Its a f350. In New York it would pass because it is a heavy vehicle. Plus the fact it is a 95. NY only checks 96 and newer. Hope this helps. I dont know what CT laws are. My honest opinion is you should fix it.


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## ppkgmsy

glfredrick;765244 said:


> Just replace the parts... They don't HAVE to cost hundreds.
> 
> There are all sorts of universal cats for sale on eBay that work just fine. Typical cost is under $50. I've used them and they pass VET. O2 sensors are the same. All it takes is a special socket that costs about $15 and a $35 sensor. Go under the truck, screw in a new one and be finished with the problem. These things don't take a dealer to fix.


I know the O2 sensors aren't a big deal but the mechanics I know have told me to be wary of the universal cats. They said they often fail quickly. Have you had a different experience over time?


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## highlander316

i don't believe Autozone's will clear codes. The ones by me (my bro works at one, I service a few) said that it is against the law for the employees to clear the codes unless they're a licensed mechanic I believe. However, you can rent the scanner, clear the code, return the scanner and get your deposit back.


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## ppkgmsy

highlander316;765593 said:


> i don't believe Autozone's will clear codes. The ones by me (my bro works at one, I service a few) said that it is against the law for the employees to clear the codes unless they're a licensed mechanic I believe. However, you can rent the scanner, clear the code, return the scanner and get your deposit back.


I bought a scanner from Sears about a year ago and it clears all the codes.


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## mayhem

sparky8370;765482 said:


> I think you misunderstood, or at least understood it differently than I did.
> My interpatation was that he needs to pass inspection so he can continue to drive his truck. And since he will be selling it shortly, he doesn't want to dump any money into it.
> I don't think his intent here is to pull the wool over the eyes of someone interested in purchasing his vehicle.


Maybe I was jumping to conclusions. Sorry if this is the case.

At any rate, fix the problems...you'll spend more time and money chasing a kluge fix than just fixing the actual problem.


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## glfredrick

highlander316;765593 said:


> i don't believe Autozone's will clear codes. The ones by me (my bro works at one, I service a few) said that it is against the law for the employees to clear the codes unless they're a licensed mechanic I believe. However, you can rent the scanner, clear the code, return the scanner and get your deposit back.


Depending on local or state laws that I may know about, there is really no such thing as a licensed mechanic...

There are certified mechanics via the dealership training network or ASE, but I've never seen any states issuing a license for a mechanic to work.

FYI, I've been an ASE certified Master Tech (which means that I've successfully passed tests in a number of individual repair areas like tune up, engine rebuilding, transmission service and rebuilding, etc.) I've also been in the industry in various capacities for over 30 years now, plus I've been a Snap On tool dealer, calling on over 200 shops. I've seen a lot more shops and mechanics than the average bear...

Clearing codes? Just do it. No biggie -- they come right back anyway.


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## Dubliner

If there is a reason for the check engine light to come on clearing the codes won't help for inspection. The computer stores all the information and after clearing the code you have to drive it a while for the computer recheck all the systems and until that happens you will fail just for that. The computers talk to each other and they are incapable of lying to each other.payup


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## glfredrick

Dubliner;765891 said:


> If there is a reason for the check engine light to come on clearing the codes won't help for inspection. The computer stores all the information and after clearing the code you have to drive it a while for the computer recheck all the systems and until that happens you will fail just for that. The computers talk to each other and they are incapable of lying to each other.payup


This is only true for the simple hand-held code readers.

With a higher-end scanner, like Snap On, etc., the entire computer can be wiped clear of codes and history codes. I do it all the time.

The drive loop that everyone is talking about is actually (depending on manufacturer, model, and year) a drive loop, which incorporates severl incidents of wide open throttle, idle time, and part throttle cruise. This can be as little as 50 miles under the right circumstances, or as much as 250 miles. When the computer tabled data is satisfied for a complete drive loop, the computer goes into closed-loop operation (versus open-loop, where the car is running based on data tables in the PCM) where the computer compensates for running conditions and tune status. It is this that is seen when the car is cleared and instantly run into the testing facility.

If this can be seen is dependent on the facilities computer capability, and they vary widely from state to state. Some may pass through with a simple code set, while others with more sophisticated scanners require a closed-loop condition in order to test.

Again, you can easily purchase the right equipment to by-pass this issue, and which will enter into the PCM any data table or condition that you like, but it is FAR cheaper, and better all around so simply fix the problems. Things that bump a person out of a VET test like 02 sensors, faulty cats, etc., are SO easily fixed, and don't have to cost huge bucks.

Typically, even a new air filter will help with faulty O2 sensor readings to a point -- it is typically not even a bad O2 that gives the reading, but rather, a dirty air filter, or a dirty MAF/MAP sensor. Both of those fixes together cost less than $50. Even more typical is the leaky gas cap, which will bump one out of most VET tests. If money is THAT tight, then something else probably needs to give in the person's life in order to afford the cost of operating a vehicle on the roadways in a legal manner.


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## Puddlejumper

glfredrick;765902 said:


> The drive loop that everyone is talking about is actually (depending on manufacturer, model, and year) a drive loop, which incorporates severl incidents of wide open throttle, idle time, and part throttle cruise. This can be as little as 50 miles under the right circumstances, or as much as 250 miles. When thg e computer tabled data is satisfied for a complete drive loop, the computer goes into closed-loop operation (versus open-loop, where the car is running based on data tables in the PCM) where the computer compensates for running conditions and tune status. It is this that is seen when the car is cleared and instantly run into the testing facility.
> 
> If this can be seen is dependent on the facilities computer capability, and they vary widely from state to state. Some may pass through with a simple code set, while others with more sophisticated scanners require a closed-loop condition in order to test.


And this is why the internet is so fun. If the guy is having the light come on for a leaky exhaust (Not likely since the pressure inside the exhaust is greater than atmospheric which is aproximately 14.7 psi) he would be popping for a lean condition. Again unlikely that air is entering upstream through an exhaust leak. Just put your hand over the end of your exhaust and feel the pressure that is coming out.

As for your loop status there is no way that a vehicle needs to drive even 50 miles let alone 250 miles to enter into closed loop. A vehicle enters into closed loop as sson as it can reliably utilize the data from the 02 sensor.

On a cold vehicle the O2 sensor is cold and needs to be warmed up in order to report reliable readings. On older vehicles this was done with just the heat from the exhaust. However this method caused problems with both the EPA and customers on vehicles where the O2 sensor was to far downstream. By 1995 most automotive manufacturers had gone to O2 sensor heaters. By 1996 and the onset of OBDII all automotive manufacturers were utilizing heated O2s.

After the vehicle has seen a reliable reading from the O2 and a few other sensors it goes into closed loop. On a vehicle that has nothing wrong with it closed loop is achieved very quickly (1-2 minutes after cold start up) if the vehicle is warm it can go into closed loop within seconds. Closed loop is where you get the best fuel economy. In open loop the PCM takes a SWAG based on coolant temp, MAP and MAF, intake temp and other sensors. Since the primary concern from the manufactorers point is to protect the engine they have the SWAG leaning rich this decreases fuel economy.

So when does the code come on. In 1995 the Ford F350 would have two tests that had to be run KOEO and KOER. An O2 code should only come up with a KOER test. Of course you can just read the code from a modern code puller. Most likely you have a failure further upstream before the combustion process takes place.


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## Puddlejumper

highlander316;765593 said:


> i don't believe Autozone's will clear codes. The ones by me (my bro works at one, I service a few) said that it is against the law for the employees to clear the codes unless they're a licensed mechanic I believe. However, you can rent the scanner, clear the code, return the scanner and get your deposit back.


They only certification that PA has is the yearly Safety and emmisions inspection certification. This has nothing to do with using a scanner and or erasing codes. There is no crime involved in erasing codes anywhere in the United States. A code is a symptom of a problem that is used by a competent technician to isolate and repair a problem. Autozone (go ahead take advice from some pimply assed kid pulling down $9.00 an hour) is blowing smoke.

To become a certified emissions inspector, you must be at least 18 years of age, have a valid driver's license, attend a PENNDOT-approved certification course and successfully complete the prescribed tests. Inspectors must take recertification courses and tests every two years to be recertified. - This is just so you can perform inspections.


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## Puddlejumper

jb1390;764984 said:


> Drive it right down the road from the emissions place, stop and disconnect the battery for 30 seconds, then get the emissions done. If you are lucky, it will take long enough to throw the code that you will be on your way home. OBD1 all you have to do is disconnect the battery or take the fuse out for the ecm to reset the codes.


My vehicle failed its OBD emission test for Readiness?

When a vehicle fails an OBD emission test due to excessive OBD monitors not ready it indicates that your vehicle's OBD system was Not Ready to perform its examination of the emission control system because the required number of monitors had not completed their analysis of the vehicle's emission control system.

What does 'Not Ready' mean ?

The OBD system continually collects data on your vehicle's everyday operation to determine if it would pass an OBD emission test. In most cases, Not Ready is a result of a battery being disconnected or a scan tool turning the MIL light off during repair work causing the monitors to be unset.

NOTE: Disconnecting the battery, a dead battery or low voltage battery or clearing the OBD computer prior to an emission test will result in an emission test failure for Readiness

Straight from CT site. However this function was not in wide use prior to OBDII and I do not believe Ford utilized it on the F350 prior to OBDII.


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## ahoron

In indiana you don't have emissions on trucks over 11,000lbs. I had to get a new plate to cheat the system. Guy at the test station told me just to get a new plate


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## mayhem

> As for your loop status there is no way that a vehicle needs to drive even 50 miles let alone 250 miles to enter into closed loop. A vehicle enters into closed loop as sson as it can reliably utilize the data from the 02 sensor.


I disagree, but it depends on the vehicle I suppose...a 95 F350 deisel probably has a hell of a lot less sensors to check than my wife's 02 Audi.

My wife's Audi had a CEL this past December. I checked the codes and reset with my ODBII scanner and the light didn't recur. Transient problem I figured like a bit of ice in a vacuum hose or somehting since usually if you reset a CEL it will just come back on within a day or so when the conditions are met. MA state inspection done in January and it failed becuase the vehicle had not yet reset to closed loop. Turns out the light cam eback on after about 5 more weeks, so I had it fixed by an authorized emissions repair center (secondary air pump failed). On the way home after putting about 20 miles on the car I stopped by the original station for a reinspection and it still reads as not ready to test.

At least in my case it definietly takes more than just warming up the car and reading the O2 sensor. State of MA website recommends that you run at least a full tnak of gas in a variety of driving conditions before returning for the retest.


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## Puddlejumper

mayhem;766047 said:


> I disagree, but it depends on the vehicle I suppose...a 95 F350 deisel probably has a hell of a lot less sensors to check than my wife's 02 Audi.
> 
> My wife's Audi had a CEL this past December. I checked the codes and reset with my ODBII scanner and the light didn't recur. Transient problem I figured like a bit of ice in a vacuum hose or somehting since usually if you reset a CEL it will just come back on within a day or so when the conditions are met. MA state inspection done in January and it failed becuase the vehicle had not yet reset to closed loop. Turns out the light cam eback on after about 5 more weeks, so I had it fixed by an authorized emissions repair center (secondary air pump failed). On the way home after putting about 20 miles on the car I stopped by the original station for a reinspection and it still reads as not ready to test.
> 
> At least in my case it definietly takes more than just warming up the car and reading the O2 sensor. State of MA website recommends that you run at least a full tnak of gas in a variety of driving conditions before returning for the retest.


You can disagree all you want it is how it is.

You are confusing Open/Closed loop for a system readiness test. When you erase a code you wipe the memory clean. All system readiness results are wiped out. So now what happens is you have to drive the vehicle through a predetermined set of criteria for the system (i.e. EGR, O2, Evap) to show ready. Each system and sensor has a unique criterion.

For example let's say I am working on a 2001 Durango and replace the O2 sensor and erase the codes. I test drive the vehicle up and down the street. While monitoring my scan tool I see that the vehicle enters into closed loop within minutes of me starting the test drive. However after I return to the garage I check the system readiness (I would never bother but I do not live in a socialist state like CT) it would show not available (or some other verbiage depending on the scan tool).

This is because the parameters for that system are as follows

O2 sensor (Operating). 
1. Engine warm up period required (vehicle would then be in closed loop). 
2.) Vehicle speed > 10 miles per hour for 1 minute, engine coolant temperature > 80Deg F. Then at idle (automatic transmission in drive), in normal memory purge cell, heated O2 must go > 0.67V, Air conditioning not fast cycling.

None of this has any bearing on the vehicle going into closed loop. Open closed loop is part of the vehicle running parameters period.

As for your wife's 02 Audi having more sensors you are correct. However this is not because of the "great sophistication" of the Audi. The vehicle in question is a 1995 Ford F350 that would fall under the pre OBDII rules. As a result your wife's Audi is required to among other things monitor itself for a cylinder misfire of > 10% and have the ability to shut off fuel to any cylinder that has a > 10% misfire. Also the Audi is required to monitor the catalytic converter for possible failure and as such has a pre & post cat O2 sensor for each cat. Even if the ford was an O2 it is exempt from many emissions requirements due to its GVWR. However a comparable Ford 1/2 ton would have just as many sensors as your wife's Audi. They may arrive at the data differently due to engineering differences (i.e. MAF vs. MAP or both). But in the end your wife's Audi has no more emission sophistication under the hood than a truck.

Regards Puddlejumper 
Memeber SAE 
FSE DaimlerChrysler 10 years
ZSPM Isuzu Motors 4 years 
GM Master Tech 
ASE Master Automobile Technician


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## mayhem

My mistake, from prior comments it looked as though you guys were using "closed loop" and "system readiness" interchangably. -1 for reading comprehension.


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## highlander316

Puddlejumper;766013 said:


> They only certification that PA has is the yearly Safety and emmisions inspection certification. This has nothing to do with using a scanner and or erasing codes. There is no crime involved in erasing codes anywhere in the United States. A code is a symptom of a problem that is used by a competent technician to isolate and repair a problem. Autozone (go ahead take advice from some pimply assed kid pulling down $9.00 an hour) is blowing smoke.
> 
> To become a certified emissions inspector, you must be at least 18 years of age, have a valid driver's license, attend a PENNDOT-approved certification course and successfully complete the prescribed tests. Inspectors must take recertification courses and tests every two years to be recertified. - This is just so you can perform inspections.


i forgot about this post. Anyway, this was coming from a few of the seniors there and the manager. What I had meant to say is, the employees there are not allowed to clear codes out, I dunno why, its just there policy I guess. Maybe it varies from district to district? I dunno.


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## brad96z28

lol dive loop dont u mean drive cycle. what the heck is a drive loop


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## Puddlejumper

brad96z28;770178 said:


> lol dive loop dont u mean drive cycle. what the heck is a drive loop


In what context are you referring to?


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