Have an intermittent problem with the check engine light. OBDII says sec. air inj. malfunction. Typically the light comes on after warm up is just about complete on cold days. The mass flow meter was replaced over the summer, switch over valve is fine whenever checked, all vacuum hoses replaced. Going a little nuts trying to diagnose this. I'm leaning towards a false reading from the coolant sender? or bad thermostat?

The supercharger doubles as an air injection pump during warm up, switches off /cycles after a warm up time. Maybe the coolant is still quite cold?....

Anyone seen this problem?

Yup. Usually it's the check valve.

Gilly

Air injection check valve, or vacuum check valve, haven't checked former, later works fine.

Air injection check valve, the big metal one, pain in the butt to get to over on the right side of the engine. Replaced alot of them.
You can remove it and test it, usually referred to as the "kazoo" test.

Gilly