Hey,
I have this persistent problem with my check enging light popping up for the "secondary air intake failure" I think the code is PO401 or PO402.
I replaced a few vacuum hoses because of dry rotting hoping that would fix the problem but the code continues to come back. I haven't notice any real change in the car but I wanna get rid of whatever is causing this.
Any suggestions would be much appreaciated...

 

You will need to replace the air pump and valve on the back of the motor to get the code to stop.

 

I don't know if the 850 is the same as the 960, but when I got a code for the secondary air, I pulled the hose from the block to the EGR Valve. I then sprayed it (saturated it more like) with PB Blaster and it freed up the valve and no codes!