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Re: options - TECH2 or OBD2 reader, or disconnect batte Posted by SWEDECAR [Email]  (#112)  [Profile/Gallery]
(more from SWEDECAR) on Fri, 24 Dec 2004 08:58:45
In Reply to: Re: options - TECH2 or OBD2 reader, or disconnect battery.., Rob D, Fri, 24 Dec 2004 08:00:30 Members do not see ads below this line. - Help Keep This Site Online - Signup |
In todays smog fighting world it is not enough to just have clean exhaust coming out of the tail pipe at the time of testing. The cars fuel computer also need to have run several tests using different sensors already installed on the car like oxygens sensors, fuel vapor recovery systems and coolant sensor to name a few.
When the car has been driven in a certain manner so that the fuel computer have had the chance to check and declared all sensors as being properly working, it sets a "readiness flag". It is a total of about 10 "flags" that needs to be set.
When you do a smog test in many States today they hook up a computer to the car and read the state of the readiness flags logged in the cars computer.
If to many readiness flags are not set (not ok, not tested) the car fails the smog test even though the tail pipe emission is within specs.
Some cars have big difficulties to set those flags (Saab 900 non turbo 96-98 and Volvo 850/70/960 96-98) and it can take weeks and month of driving the car before it happens. I have driven my Volvo 960 for 4 years now without it happening.
Every time you reset the fault codes in the cars computer you also wipe out the state of readiness flags and the car needs to be driven an X amount of miles again before they are set.
If you only "read" the codes (not resetting) you are good to go. That way you can repair what problem the fault code indicated and may get away with a much shorter drive to make the check engine light go out.
So keep that in mind when it is time for a smog check and you have a check engine light on. Don't just have the light reset and then drive to the smog station. You might fail the smog test just because of that if your State uses the new rules.
Anders
posted by 24.127.89...
, Fri, 24 Dec 2004 09:09:00, Fri, 24 Dec 2004 08:58:45 <-- Viewing This Message
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