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Seville STS 2001, Eldorado 1997
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394 Posts
Discussion Starter #1
I drove car to a emission test facility in Chicago area and drove about 25 minutes at about 30 mph and test got rejected since some of the System Monitors not ready (Heated Oxygeon sensor, Oxygen Sensor, Evaporative Control System, and Secondary Air Systems). The other 5 System montors were in ready state (Comprehensive Component, Engine Misfire, Catalac Converter, ....). They asked me to come back for retest. Are there any instructions from any Cadillac repair manual what to do so that the System Monitors go to ready state. Will dirving at high speed help or disconnecting battery etc. I will appreciate your ideas.

Thanks
John
 

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85 Coupe Deville 4.1 V8 & 4.3 V6 Deisel & 1970 Eldorado
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773 Posts
Did you reset your codes? Disconnect your battery? The computer keeps track of this and will set a code that the inspection system will see. This keeps someone from resetting their codes right before inspection trying to trick the system. The car will have to be driven a bit to clear this code. You can not clear this "freshness" code.
 

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Seville STS 2001, Eldorado 1997
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394 Posts
Discussion Starter #3
Yes, I cleared codes just after starting the car and then drove for about 20 minutes or so before the test. Do you think that clearing the codes might have been detected. In fact there was no code but I did cleared all. So do you think that I should not clear next time before the test?
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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19,495 Posts
Yes, I cleared codes just after starting the car
well - there's yur problem - right there :thepan:

Do you think that clearing the codes might have been detected.
yep -

So do you think that I should not clear next time before the test?
yep -
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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69,056 Posts
Any time you "clear codes" you wipe out the entire emissions monitoring memories database. It takes a dedicated "GM drive cycle" or about a week of normal daily commuting to have all the required tests and checks done/run in order to set all the "ready" flags in the emissions database.

NEVER clear codes in hopes that will pass an emissions test - it won't. Ever. If the car has emissions faults/codes, repair the system(s) and drive a week or so before attempting a test.

Some checks (for code faults) take several start-run-drive events to complete, and repaired codes will self-clear in 30, 40, or 50 successful start-run-drive events.

You might get away with clearing codes to extinguish a SES warning if the emissions test station uses the old tailpipe test - but you're sunk if it uses the OBD port test set.

For more info, Google "cadillac forums gm drive cycle and emissions tests" or something close.
 

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'16 VSport (wife's), '10 Escalade, '97 & '02 SS Camaro's, '15 Silverado LTZ
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1,132 Posts
I was told it takes about 50 miles to go through the "drive cycle". I've read that its best to take about a 30-40 drive on the interstate and then go straight to the Emission station to get the cleanest readings.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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69,056 Posts
A GM Drive Cycle is a very dedicated specific series of starts, stops, accelerations, coasts, cruises, equipment operation.

It is impossible to perform in a city or near suburban environment.

Google it. I believe that it's also defined in a few posts in Tech Tips.

The advice on taking a decent 'warmup drive' prior to an emissions test takes into account both types - the old tailpipe sniffer and the test port type. It is also sound advice - do a highway run just before a test and beware of magic potions and snake oils used to "clean the engine and exhaust for a test".
 

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1998 Cadillac Seville SLS, Northstar
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4 Posts
I have a solution for passing emissions tests. I have not been passing emissions on my '98 Cadi Seville Northstar, because of the P0741 code. So I read several forum posts. One suggestion for preventing the checking light after clearing code(s), is to drive car under 41mph, which is when the P0741 code will generate again. It would be dangerous to go 41mph or less on the highway. And The code and SES light came back up when I tried to perform the GM driving cycle on the highway.

Instead last night, I drove around an area in town for about 80 miles to ready the car again, after I cleared the P0741 code. I was able to manage staying under 41mph the entire time. It took me about three hours to get 80 miles in town. But no engine light came on. This morning I took the car for emissions retesting, staying under 41mph heading to the test station, and it passed!

So for readiness after resetting codes, all you need to do is drive the car for about 80 miles, stay under 41 mph when and where possible, to prevent your P0741 code if you are getting it. And then you can go back for retest. This saved me a whole lot of time and a whole lot of money.

I am assuming that driving 80 to 100 miles on one run, should be good enough to reset readiness for any make or model, instead of driving around for a week or two, waisting time and gas. Staying under 41mph is only necessary for the P0741 code. That code has not caused any driving problems for me, it was just an issue with passing emissions.

Marv
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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26,323 Posts
A driving cycle does not require any specific total mileage to be driven. It requires that all emission related monitored parts/systems have a chance to either function or set a fault code. A driving cycle can take days, or less than 15 minutes. Google GM driving cycle for more info.

Post #9
 

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White Diamond '03 DHS (with DTS floor shift)
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PLUS, I could be wrong, but I'm not sure that will work on a 2000+ car.
 

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Seville STS 2001, Eldorado 1997
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394 Posts
Discussion Starter #13
Finally I was able to get the car passed. Simply drove about 3 weeks once my first car test failure and drove on highway for about 30 minutes prior to the test. Thank you all for your feedback.

Thanks
John
 
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