OT - Check Engine Lights, Computer Codes and Passing Inspection

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I asked 5 different "experts" the same question and got 3 different answers.
"If a vehicle has an intermittent Check Engine Light from an Evap code, and the light is off when the vehicle gets inspected, will the inspection computer still pick up the code causing the vehicle to fail the inspection?"
For those that don't know, Evap codes are the codes that would come on if the gas cap was loose or the gas tank fill tube was cracked, etc. Any leak in the fuel system could cause an Evap code.
In the case of the vehicle in question, the light comes on about once a month, stays on for few days and then goes off. It doesn't seem to be related to any one specific action, such as filling the tank all the way, not filling the tank all the way, driving hard, driving easy, etc. It really seems to be random.
Here‘s a list of who I asked and what they said:
A well known auto parts store and a local service station both said it's hit or miss, you never can tell if it will pass.
A different well known auto parts store and a local service station where a huge part of their business is "instant inspections" but that also does repairs, both said it will definitely fail.
A third local service station (a big, always busy operation) said if the light is off it will definitely pass.
What do you folks think?
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On 01/04/2014 05:33 PM, DerbyDad03 wrote:

The light will come on if there is an error condition
so if the light is off when the car is inspected it should pass.
(Obviously not true if there is a lose connection to the bulb, but that is not likely to be the case)
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On 1/4/14, 7:03 PM, philo wrote:

When I use my own code reader on my 1994 Olds or the 1994 GMC Jimmy, it reads out both *current* codes, and *history* codes. The history codes stay until reset using the code reader.
So it would seem possible if you have stored history codes, the inspection just might pick up on them, whether the lite is on or not.
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That's what the people who said it would "definitely fail" said. They said the codes would still be in the vehicle's computer history and the inspection machine would pick them up.
Once we get a few more answers/opinions, I'll post the results of a real life situation.
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On 01/04/2014 07:44 PM, DerbyDad03 wrote:

What if rather than being an intermittent problem...you found the actual cause and fixed it? The car is now fixed, but the previous codes are still in memory. Why would they fail you? Basically the car either passes or fails, I don't see what prior history has to do with it.
A friend of mine has been trying to get her car passed for five months. She recently had a good day and finally got it passed. She lucked out...but still all the previous error codes must have still been there.
Guess you will know when you get there.
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That's a good point. In that scenario the car would have to pass.
Or as a lawyer might say, "Objection! Prior bad acts are not admissible and would be prejudicial."
I'm not a lawyer but I watched one on TV.

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On Sat, 04 Jan 2014 20:06:19 -0600, Gordon Shumway

If the problem is fixed and the codes are not erased it will not pass. If the codes are erased and the monitors are not reset (drive cycle) it will not pass. The E-Test as it exists in Ontario, anyway, is a farce

I can tell with 99% certainty if a car is going to pass, in about 10 minutes.

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On Sun, 5 Jan 2014 01:44:51 +0000 (UTC), DerbyDad03

If you erase the codes the codes are gone - period. The code reader reads current codes and "incipient" codes. To turn on the light and "set" a code the error must be found a certain number of times in a given time period. Untill that happens they are "incipient" codes. Before a code can be set, certain conditions need to be met to set the "monitors"that monitor the sensors. Until the monitor is set, the computer cannot set a code or even an incipient code. A drive cycle needs to be run through to set the monitors - and if you keep certain parameters outside the boundaries required to set the monitor you can reset all the monitors EXCEPT the evap monitor if you want to. If your test allows one monitor to be unset and still pass, you can pass with bad evap. If you run the drive cycle with wrong temperatures, or the tank too full or too empty, the evap monnitor will not set.
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I'm not sure to which post I should reply with my actual experience, so I'll probably post it in more than one response.
2004 Honda Odyssey. The Evap code condition has been present and intermittent for more than a year.
For my 2013 inspection I took it to a shop owned by a guy who used to work in a Honda dealer's service center. The light was on at the time. I told him about the Evap code and the intermittent nature of the problem. He told me that he would reset the light, drive the vehicle for a few miles and if it didn't come back on, he would inspect it. The vehicle passed the inspection.
This year, I waited for the light to stay off for about a week and then took it for an inspection at a local service center. I didn't say anything about the light or the intermittent nature of the problem. It passed the inspection. This was the shop that later told me that passing an inspection with an intermittent check engine light was "hit or miss". I asked it as a hypothetical question, not telling him that the problem was the vehicle that just passed the inspection.
So, bottom line, however the inspection system deals with past, current or future codes, this vehicle passed inspection twice even though the problem still exists.
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On 01/05/2014 09:55 AM, DerbyDad03 wrote:

Yep, just as I predicted.
From experience I know that "what should be true" or "what should not be true" have little bearing on "what actually is true".
Proves I have a logical mind ....now convince my wife of that <G>
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On Sun, 5 Jan 2014 15:55:45 +0000 (UTC), DerbyDad03

When he drove the car he most likely did the "drive cycle" and the evap monitor did not reset - So it passed.

Yours likely got through the monitor reset without having the intermittent happen - so no codes were set Mostvehicles reset the monitor and code after X miles or X restarts with no recurrence. This is true of Evap codes that can be caused by a bad or loose gas cap.(PO440, 442, 445 and 455 are examples)
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Your 1994 Olds or Jimmy sligthly predates OBDII which requires predates certain behavior, FWIW, but consider this. Say the vehicle does have a history code, to use the OPs example an evap code, and it was caused by a defective gas cap. So if the OP replaced the gas cap, fixing the problem, should the inspection then fail because of a history code that predated the fix?
Just askin...
--
Often wrong, never in doubt.

Larry W. - Baltimore Maryland - lwasserm(a)sdf. lonestar. org
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On Sunday, January 5, 2014 2:37:09 AM UTC-5, Larry W wrote:

I think the answer is that it depends. If you fixed the gas cap and drove 2 miles over to the inspection station, then it will surely fail, because the computer doesn't know it's been fixed. When the computer first notices something wrong like this, it records it as a "pending" fault. If the condition persists long enough, then it sets an actual fault code and may also turn on the check engine light, depending on what the fault actually is. In the case of the leaking gas cap, it would turn on the check engine light.
Usually, the fault would get cleared manually when the problem is identified and fixed. If it's not cleared manually, then I believe the computer would clear it eventually, after it's seen it being normal for a certain period of time. Not sure about that last part though. I do know that the evap system takes a much longer time to accumulate data than many of the other parameters. If you clear/reset all the monitored data, to pass inspection, the car has to be run/driven enough to set all the necessary monitors. The evap system one is the last to get set. I've seen discussions an no one seems to know for sure what it takes to set it, ie is it engine running time, distance driven, startup/shutdown cycles, etc.
In the case in question, if it were me and the immediate objective was to get it through inspection, I'd just hook up my code reader, clear the code, and take it to be inspected before it came back on.
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On Sun, 5 Jan 2014 07:37:09 +0000 (UTC), snipped-for-privacy@sdf.lonestar.org (Larry W) wrote:

error occurs on an OBD2 vehicle it will pass. Here in Ontario Pre OBD2 vehicles still get sniffed.
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Retired wrote:

That is how it works. Old code is stored in the memory until cleared. And OP, gas tank cap might be faulty. I'd connect the code reader and clear the memory B4 going in for inspection. My code reader is a laptop with OBD II utility software. I built a USB 2 interface kit and got a copy of software from eBay. Just code reading simple ones are freeware.
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wrote:

GUARANTEE the car will fail. 100%
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I'm not sure to which post I should reply with my actual experience, so I'll probably post it in more than one response.
2004 Honda Odyssey. The Evap code condition has been present and intermittent for more than a year.
For my 2013 inspection I took it to a shop owned by a guy who used to work in a Honda dealer's service center. The light was on at the time. I told him about the Evap code and the intermittent nature of the problem. He told me that he would reset the light, drive the vehicle for a few miles and if it didn't come back on, he would inspect it. The vehicle passed the inspection.
This year, I waited for the light to stay off for about a week and then took it for an inspection at a local service center. I didn't say anything about the light or the intermittent nature of the problem. It passed the inspection. This was the shop that later told me that passing an inspection with an intermittent check engine light was "hit or miss". I asked it as a hypothetical question, not telling him that the problem was with the vehicle that just passed the inspection.
So, bottom line, however the inspection system deals with past, current or future codes, this vehicle passed inspection twice even though the problem still exists.
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That's my understanding too, except the code also disappears if the problem is gone after 100 turns of the key to Start or On, not sure which.
So if Phil's friend drives every day that's maybe 5 days after the last visible light. Well, he didn't say how much the light was on.

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wrote:

I meant 25 days.

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I'm not sure to which post I should reply with my actual experience, so I'll probably post it in more than one response.
2004 Honda Odyssey. The Evap code condition has been present and intermittent for more than a year.
For my 2013 inspection I took it to a shop owned by a guy who used to work in a Honda dealer's service center. The light was on at the time. I told him about the Evap code and the intermittent nature of the problem. He told me that he would reset the light, drive the vehicle for a few miles and if it didn't come back on, he would inspect it. The vehicle passed the inspection.
This year, I waited for the light to stay off for about a week and then took it for an inspection at a local service center. I didn't say anything about the light or the intermittent nature of the problem. It passed the inspection. This was the shop that later told me that passing an inspection with an intermittent check engine light was "hit or miss". I asked it as a hypothetical question, not telling him that the problem was the vehicle that just passed the inspection.
So, bottom line, however the inspection system deals with past, current or future codes, this vehicle passed inspection twice even though the problem still exists.
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