Ok, so a PID 01 00 query to my ECU reveals the following PID codes are available to poll: 1, 3, 4, 5, 6, 7, 11, 12, 13, 14, 15, 16, 17, 19, 21, 28, and 32.

Numbers up through 15 I have (pretty much) figured out (e.g., 5 = coolant temp, etc.). Anyone have any thoughts on what codes 16, 17, 19, 21 and 28 unlock?
Thanks,
-- scooter

From my scan tool:
$10 (16d) - MAF
$11 (17d) - throttle position
$13 (19d) - O2SLOC - location of O2 sensors (??)
$15 (21d) - O2S12 SHRTFT12 -- O2 for bank 1, sensor 2 output and short term fuel trim
$1C (28d) - OBD2SUP -- which OBD version supported

thanks

scooterforever,
Just wanted to point out that if you examine the data from PID $20 (32d), you'll see that it is non-zero and has a bit set which indicates the ECU supports PID $24 (36d). PID $24 has data from your front A/F sensor. See this page (http://www.skiffcraft.com/disco/images/slam/cars/imprezapdf/2%20-%20Engine%20H4%20(DOTC%20TURBO)/Engine%20Section%20H4%20(Diagnostics)/MSA5T0412A35416.pdf) for details. The page at http://www.obddiagnostics.com/obdinfo/pids1-2.html is also helpful.