2007 and newer Subaru's use CAN (Controller Area Network)
Beginning in 2008, the Society of Automotive Engineers (SAE) requires 100% of the vehicles sold in the USA to use the CAN Bus communication protocol
I'm still trying to educate myself on this, but basically it seems like any car with CAN is going to give EVERYTHING up.
All parameters are easily read.
This looks like bad news for tuned vehicles.
Got the Info below from a post I found
on another forum after doing a search:
This is what will be read using Mode $09:
- CAL ID for each segment.
- CVN for each segment.
- VIN of your vehicle.
they then use the VIN to look up a database containing valid CAL ID and CVN values for your VIN
(this is already in place for 2005+ cars)
if your car is a 2005+ they will definitely see the differences in CVN values.
if your car is 2000-2005 they may still be able to pick up on these differences, even tho they didn't legislate for a database for cars prior to 2005; that doesn't mean they don't have a means of looking up and checking (they have had the ability to store the CAL ID and CVN values from all your previous smog tests, and they have the computing ability to detect differences, they just can't necessarily compare them to the OEM values)
Cars after 2005: they legislated that the OEM's provide the cal ID's and CVN's for each VIN in generalized database format; the BAR can compare values read from vehicle against the generalized database.
for your car to pass the PCM had to do these things:
- show no codes present,
- set all the Readiness tests to Ready (2002+ one is allowed to be Not Ready),
- set all the O2 test results to values indicating pass;
- control fueling/timing to produce emissions levels that are within the sniffer limits.
A scanner is also able to read these things (defined by OBD-II since its inception):
- Mode 6 test results (theses will show that you have codes/sensors turned off),
- calibration ID's and CVN's;