P0410 and P1411 Question
 

Both codes suggest implausible signal in the secondary air system. Specifically, what signal is implausible? The answer might help me sort out a CEL problem that so far has defied solution.

Causes
 

Secondary air injection pump is not
triggered
Secondary air injection pump does
not function
Air supply lines restricted
Electric change-over valve does not
function
Air change-over valve does not
function
Vacuum system leaking

According to some Porsche technical information I found, the only signal the car monitors when it checks the air injection system comes from the O2 sensors. A low signal level on the O2 sensors means oxygen is present so the car's computer expects to see the O2 sensor levels fall when it activates the air pump. This is monitored once per key cycle. Send me a PM if you need the actual tech document.