The car had coded a P0491 SAI (Combi valve) code - low flow. I initially diagnosed the sensor and hose as a failure. The flow sensor was covered with water, the code occurred during freezing weather. So I swapped out the hose (there is an updated hose and sensor). Cleared codes, code came back. Checked Combi valve, applied 12volts to the Combi valve solenoid, no motion. Verified with an active test from a high level scan tool. There is a TSB about re-flashing the ECU/PCM, I don't have that ability right now, so I went with replacing the Combi valve.

Job isn't brutal, but if you have big hands, or lie down easily this will be filed under "too hard" , some of the 10mm bolts are made for long-armed fools like me. It's tight. A t-30 with a long extension is needed for the exhaust tube to the Combi valve. Thanks to @fcpeuro for the quick parts!