Sinology

so i tried to smog my car today and the smog station attendant told me that the computer can't read the emission's sensors and that i would fail the test if he tested ... he told me that i have to drive the car on the freeway for 30-40 minutes, the more the better... so before i go out and waste all this gas and money i thought i would ask if anyone heard of this? any help would be nice

Sinology

oh he also said that because i changed my battery it reset my ecu... dunno how true this is

Relic1

100% true. when the ECU looses power it resets everything.
To have the ECU clear the readyness flags (which makes the test valid for the smog station) you have to drive the car for a few days. (two driving cycles)

thesmogman

Yes it is very true. To pass the OBDII tests in California the check engine light has to work properly and 66% of the monitors need to be set to complete.

In the ECU program there are monitors. There are three that run all the time and set quickly. Then there are some more 5 to 9 of them and these usually take 75 to 100 miles to set to complete

When you remove power to the ECU or erase codes it wipes them out and set's them to incomplete.

The smog machine does all the checking and the tech has no control over this part of the test. So don't blame the tech!

He could of taken your money and failed you and charge you for a retest too. The tech did do you a favor.

Sinology

cool stuff...i guess ill be going for a cruise tomorrow...one more question...how will i know when its ready for the smog test?

thesmogman

You need a OBDII reader to check them. Just ask the tech to check them before the test like they did today.

Just drive 100 mi and you should be fine.