Smog test: Vehicle failed the MIL/Check Engine Light due to failureto successfully complete all OBD self tests

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Old 15 May 2010, 03:09 am   #1 (permalink)
condor_222@yahoo.com
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Default Smog test: Vehicle failed the MIL/Check Engine Light due to failureto successfully complete all OBD self tests

Dear Experts,

I've had some more adventures with my 99 Lexus ES300.
Now, about 107K miles.

I had the alternator changed in the winter.

Some weeks later, I was driving cross country.
I got a check engine light.

I checked the code. It was the P0420,
Catalyst System Efficiency Below Threshold (Bank 1)


I pulled out my OBD tool, and erased it.
But It came back again a few times.
Sometimes, it took only about 40 miles.
Another time, it took 200 miles.
I probably got the code, and erased it at least 4 times.

It only happened when I was driving cross country, all day long.
Since I returned to the city, I have not got the code.

Today, I went to go get a smog check in California.

Before I left, I connected the OBD to my laptop, and erasad all codes,
just to be sure.

When I went for the smog test, everything was fine, except I failed:

Vehicle failed the MIL/Check Engine Light due to failure to
successfully complete all OBD self tests.


I've since been reading more about the OBD here:
http://www.smogtips.com/functional_inspection.cfm

One possibility I read there:

Step D. Drive your vehicle for one week under normal driving
conditions. During this period the emissions computer is gathering
data and re-learning your vehicle's emissions components and systems.
The emissions computer OBDII (on-board diagnostics) system must
complete at least one drive cycle (in some cases two or three). A
drive cycle is a sequence of internal tests which the emissions
computer runs while your vehicle is being driven. This insures all
emissions systems are functioning properly. Proper "readiness flags"
are set as the computer completes it's cycles. Test cycles are unique
to a vehicle. Certain cycles run under very strict parameters, and may
require extended driving time to trigger on. Cycle data and readiness
flag information is available through your dealership's service
department. The data vary widely.


My questions.

1) Does Step D make sense, given that I'd erased the codes? If I
do drive the car for a few days like this, should I be able to pass
the test?

2) If I erased all the codes, are they really all erased? Or, is
there still some log about them? That they were there, I erased them,
and they are just flagged inactive now?


Thanks a lot!


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Old 15 May 2010, 06:42 am   #2 (permalink)
Jeff Strickland
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Default Re: Smog test: Vehicle failed the MIL/Check Engine Light due to failure to successfully complete all OBD self tests


<condor_222@yahoo.com> wrote in message
news:735e72ef-774f-4087-b171-6bd7232609ad@j36g2000prj.googlegroups.com...
> Dear Experts,
>
> I've had some more adventures with my 99 Lexus ES300.
> Now, about 107K miles.
>
> I had the alternator changed in the winter.
>
> Some weeks later, I was driving cross country.
> I got a check engine light.
>
> I checked the code. It was the P0420,
> Catalyst System Efficiency Below Threshold (Bank 1)
>
>
> I pulled out my OBD tool, and erased it.
> But It came back again a few times.
> Sometimes, it took only about 40 miles.
> Another time, it took 200 miles.
> I probably got the code, and erased it at least 4 times.
>
> It only happened when I was driving cross country, all day long.
> Since I returned to the city, I have not got the code.
>
> Today, I went to go get a smog check in California.
>
> Before I left, I connected the OBD to my laptop, and erasad all codes,
> just to be sure.
>
> When I went for the smog test, everything was fine, except I failed:
>
> Vehicle failed the MIL/Check Engine Light due to failure to
> successfully complete all OBD self tests.
>
>
> I've since been reading more about the OBD here:
> http://www.smogtips.com/functional_inspection.cfm
>
> One possibility I read there:
>
> Step D. Drive your vehicle for one week under normal driving
> conditions. During this period the emissions computer is gathering
> data and re-learning your vehicle's emissions components and systems.
> The emissions computer OBDII (on-board diagnostics) system must
> complete at least one drive cycle (in some cases two or three). A
> drive cycle is a sequence of internal tests which the emissions
> computer runs while your vehicle is being driven. This insures all
> emissions systems are functioning properly. Proper "readiness flags"
> are set as the computer completes it's cycles. Test cycles are unique
> to a vehicle. Certain cycles run under very strict parameters, and may
> require extended driving time to trigger on. Cycle data and readiness
> flag information is available through your dealership's service
> department. The data vary widely.
>
>
> My questions.
>
> 1) Does Step D make sense, given that I'd erased the codes? If I
> do drive the car for a few days like this, should I be able to pass
> the test?
>
> 2) If I erased all the codes, are they really all erased? Or, is
> there still some log about them? That they were there, I erased them,
> and they are just flagged inactive now?
>
>


The codes ARE erased, but there are 8 monitors that have to complete before
they will Smog Test your car. The fact that the monitors have not completed
is by itself reason to fail smog. You have to complete the drive cycles, and
this takes time. I think you can have two incomplete monitors, and your scan
tool should show which monitors are complete and which are ongoing.

What you have not done is fixed the underlying issue of the post-CAT O2
Sensor.

I'm not certain, but I'd like to throw this out for consideration.

On your cross country trip, did you fill the tank with E85 -- that's
gasoline that's 85% ethanol? I'm not sure, but maybe 85% ethanol is a
problem for the CAT. If you found plain old leaded Regular, or leaded
Premium, and put it in your car, this will destroy a CAT. Bottom line is,
you either have a bad CAT or a bad sensor.




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Old 15 May 2010, 08:53 am   #3 (permalink)
Kruse
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Default Re: Smog test: Vehicle failed the MIL/Check Engine Light due tofailure to successfully complete all OBD self tests

On May 15, 6:42*am, "Jeff Strickland" <crwlrj...@yahoo.com> wrote:

> If you found plain old leaded Regular, or leaded
> Premium, and put it in your car, this will destroy a CAT. Bottom line is,
> you either have a bad CAT or a bad sensor.


On a cross-country trip, where would he find regular leaded or leaded
premium?
Tetra ethyl lead was phased out YEARS ago.

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Old 15 May 2010, 09:08 am   #4 (permalink)
e.meyer
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Default Re: Smog test: Vehicle failed the MIL/Check Engine Light due tofailure to successfully complete all OBD self tests

On May 15, 3:09*am, condor_...@yahoo.com wrote:
> Dear Experts,
>
> I've had some more adventures with my 99 Lexus ES300.
> Now, about 107K miles.
>
> I had the alternator changed in the winter.
>
> Some weeks later, I was driving cross country.
> I got a check engine light.
>
> I checked the code. *It was the P0420,
> Catalyst System Efficiency Below Threshold (Bank 1)
>
> I pulled out my OBD tool, and erased it.
> But It came back again a few times.
> Sometimes, it took only about 40 miles.
> Another time, it took 200 miles.
> I probably got the code, and erased it at least 4 times.
>
> It only happened when I was driving cross country, all day long.
> Since I returned to the city, I have not got the code.
>
> Today, I went to go get a smog check in California.
>
> Before I left, I connected the OBD to my laptop, and erasad all codes,
> just to be sure.
>
> When I went for the smog test, everything was fine, except I failed:
>
> Vehicle failed the MIL/Check Engine Light due to failure to
> successfully complete all OBD self tests.
>
> I've since been reading more about the OBD here:http://www.smogtips.com/functional_inspection.cfm
>
> One possibility I read there:
>
> Step D. Drive your vehicle for one week under normal driving
> conditions. During this period the emissions computer is gathering
> data and re-learning your vehicle's emissions components and systems.
> The emissions computer OBDII (on-board diagnostics) system must
> complete at least one drive cycle (in some cases two or three). A
> drive cycle is a sequence of internal tests which the emissions
> computer runs while your vehicle is being driven. This insures all
> emissions systems are functioning properly. Proper "readiness flags"
> are set as the computer completes it's cycles. Test cycles are unique
> to a vehicle. Certain cycles run under very strict parameters, and may
> require extended driving time to trigger on. Cycle data and readiness
> flag information is available through your dealership's service
> department. The data vary widely.
>
> My questions.
>
> 1) * Does Step D make sense, given that I'd erased the codes? * If I
> do drive the car for a few days like this, should I be able to pass
> the test?
>
> 2) *If I erased all the codes, are they really all erased? *Or, is
> there still some log about them? *That they were there, I erased them,
> and they are just flagged inactive now?
>
> Thanks a lot!


Your mistake was erasing the codes immediately before going for the
test. Several parameters are not set to ready until a "drive cycle" is
completed. Next time, if the check engine light is not on, leave well
enough alone. If you complete the cycle and the check light does not
come back on, it should pass.

As far as number 2, if you successfully reset the computer, then yes,
the codes are gone. If there is a problem the code will be right back
in there though. Before you go back for a retest, read the codes but
none show up, do not reset.
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Old 15 May 2010, 09:18 am   #5 (permalink)
jim
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Default Re: Smog test: Vehicle failed the MIL/Check Engine Light due to failureto successfully complete all OBD self tests



Jeff Strickland wrote:

> Bottom line is,
> you either have a bad CAT or a bad sensor.


Not necessarily. Exhaust leaks and corroded electrical connection are
also possible causes of P0420 DTC.

-jim
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Old 15 May 2010, 11:59 am   #6 (permalink)
Hachiroku ハチロク
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Default Re: Smog test: Vehicle failed the MIL/Check Engine Light due to failure to successfully complete all OBD self tests

On Sat, 15 May 2010 01:09:27 -0700, condor_222 wrote:

> One possibility I read there:
>
> Step D. Drive your vehicle for one week under normal driving conditions.
> During this period the emissions computer is gathering data and
> re-learning your vehicle's emissions components and systems. The emissions
> computer OBDII (on-board diagnostics) system must complete at least one
> drive cycle (in some cases two or three). A drive cycle is a sequence of
> internal tests which the emissions computer runs while your vehicle is
> being driven. This insures all emissions systems are functioning properly.
> Proper "readiness flags" are set as the computer completes it's cycles.
> Test cycles are unique to a vehicle. Certain cycles run under very strict
> parameters, and may require extended driving time to trigger on. Cycle
> data and readiness flag information is available through your dealership's
> service department. The data vary widely.
>
>
> My questions.
>
> 1) Does Step D make sense, given that I'd erased the codes? If I do
> drive the car for a few days like this, should I be able to pass the test?
>
> 2) If I erased all the codes, are they really all erased? Or, is there
> still some log about them? That they were there, I erased them, and they
> are just flagged inactive now?
>
>
> Thanks a lot!


It knows the codes have been reset recently. And it also has a count of
how many 'driving cycles' are on the ECU. In Mass I think it requires 4
driving cycles in order to pass (for some reason the number 2 is stuck in
my head, but I think they have made it 4.) The ECU keeps track of driving
cycles and the OBDII reader counts them.

Drive the thing for a couple days and then go for a retest. As long as the
MIL is off, it should pass.


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Old 15 May 2010, 12:44 pm   #7 (permalink)
Scott Dorsey
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Default Re: Smog test: Vehicle failed the MIL/Check Engine Light due tofailure to successfully complete all OBD self tests

Kruse <kruse@kansas.net> wrote:
>On May 15, 6:42=A0am, "Jeff Strickland" <crwlrj...@yahoo.com> wrote:
>
>> If you found plain old leaded Regular, or leaded
>> Premium, and put it in your car, this will destroy a CAT. Bottom line is,
>> you either have a bad CAT or a bad sensor.

>
>On a cross-country trip, where would he find regular leaded or leaded
>premium?
>Tetra ethyl lead was phased out YEARS ago.


Out here we have a couple places that sell it for farm vehicles. Not
legal for road use.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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Old 15 May 2010, 04:35 pm   #8 (permalink)
Jeff Strickland
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Default Re: Smog test: Vehicle failed the MIL/Check Engine Light due to failure to successfully complete all OBD self tests


"Kruse" <kruse@kansas.net> wrote in message
news:343c92da-e3a9-4b60-be98-5c23246d40db@o1g2000vbe.googlegroups.com...
On May 15, 6:42 am, "Jeff Strickland" <crwlrj...@yahoo.com> wrote:

> If you found plain old leaded Regular, or leaded
> Premium, and put it in your car, this will destroy a CAT. Bottom line is,
> you either have a bad CAT or a bad sensor.


On a cross-country trip, where would he find regular leaded or leaded
premium?
Tetra ethyl lead was phased out YEARS ago.



<JS>
The point is, your car demands UNLEADED.

Some of the farming communities might make leaded gas available for
tractors. You shouldn't be able to even put the pump nozzle in the car, so
this is a very remote thing to consider. But consider it, then toss it
aside.

If you can remember a time that the nozzle didn't fit well into the filler
hole, that's a clue that maybe you got leaded gas.

I agree though that it's not a likely thing to have happened.




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Old 15 May 2010, 04:37 pm   #9 (permalink)
Jeff Strickland
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Default Re: Smog test: Vehicle failed the MIL/Check Engine Light due to failure to successfully complete all OBD self tests


"jim" <"sjedgingN0Sp"@m@mwt,net> wrote in message
news:9tqdnSdsatigMHPWnZ2dnUVZ_v6dnZ2d@bright.net.. .
>
>
> Jeff Strickland wrote:
>
>> Bottom line is,
>> you either have a bad CAT or a bad sensor.

>
> Not necessarily. Exhaust leaks and corroded electrical connection are
> also possible causes of P0420 DTC.
>



Yeah, sure. Out here in California, we don't have much trouble with stuff
corroding, but we all know it happens.

Seems to me that one would hear an exhaust leak large enough to cause a code
that says the CAT was bad.





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Old 15 May 2010, 07:00 pm   #10 (permalink)
jim
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Default Re: Smog test: Vehicle failed the MIL/Check Engine Light due to failureto successfully complete all OBD self tests



Jeff Strickland wrote:

> "jim" <"sjedgingN0Sp"@m@mwt,net> wrote in message
> news:9tqdnSdsatigMHPWnZ2dnUVZ_v6dnZ2d@bright.net.. .
> >
> >
> > Jeff Strickland wrote:
> >
> >> Bottom line is,
> >> you either have a bad CAT or a bad sensor.

> >
> > Not necessarily. Exhaust leaks and corroded electrical connection are
> > also possible causes of P0420 DTC.
> >

>
> Yeah, sure. Out here in California, we don't have much trouble with stuff
> corroding, but we all know it happens.


Maybe he's not in Cal.



>
>
> Seems to me that one would hear an exhaust leak large enough to cause a code
> that says the CAT was bad.


I have no way of knowing if he hears an exhaust leak or not. A small leak in the
right location would be enough.

-jim




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