I don't know about other makes, but all GM's OBD2 computers have the VIN in them. Whenever we replace an ECU, you have to program it and manually enter the VIN into the program. You won't fail for having another ECU in your vehicle, it just can't have codes and all the required systems have to be "ready". I'm pretty sure the DEQ took into account that you can buy used computers from the junkyard and such. But if they see that one place is doing a lot of emissions with non-matched VINs, they will investigate. Nothing will happen to you since, technically you passed, but the inspector will get in trouble if he was doing something shady. We had it happen here, one of our guys was using one car for a bunch of inspections to save time. Suspended his emissions liscense for a year.

 

thats weird, i have an ESP machine and only time it checks vins is when it dials up to the DMV's server to get info on the car using the vin that you scanned in or typed in when the DLC is hooked up it only checks for codes, then retrieves readiness status and is done with it what machine do you guys use?

 

I'm not sure which model analyzer it is but I'm sure we all use the same ones. It said "checking VIN" for about a second right after the readiness test. It's the last step in the OBD2 test. I never really noticed it until I recently because of this thread.

 

whats are the steps.. what if i do pass the obd2 monitor readiness test? what then, what else could i fail for?

 

You could still fail for no cat (visual inspection), bad gas cap, smoking from exhaust or crankcase, no DLC port, CEL/SVS light on or no light at all (must light up with key in "on" postion/engine off).