Error Codes 9 & 40 in plain English?
 

I'm getting error codes 9 (Water Thermosensor
open or short circuit) and 40 (Purge control Solenoid
open or short circuit). What do these mean in plain English? I think I know what a Water Thermosensor is. But what is a "Purge control solenoid"?? Would this have anything to do with me only making 1psi on the 1st turbo and 5psi on the 2nd? Thanks in advance!!

the turbo system is controlled by the follwoing solenoids: turbo precontrol, turbo control, wastergate control, charge control and charge relief solenoid valves. All of these solenoids are controlled by the Powertrain Control Module. the MItchell repair manual had this information.

the purge control solenoid, according to the manual, assists the car in the prevents of fuel vapor escape (the fuel evaporation system). thus, i dont see a connection between the purge control solenoid and your car making less boost.

but then again, its difficult to say, because the bad signals that the ecu is getting could be the cause of low boost somehow. my suggestion would be for you to replace the waterthermosensor and the purge control solenoid, and while you are at it, you should check all of the solenoids and make sure they are working properly (its very possible that another one, which controls boost, is not working properly-solenoids on an average would have the same lifetime, so if one goes the rest of them are probably near their end). and you should also upgrade all the vacuum hoses to silicone ones.

the waterthermosensor is around $40(make sure the mazda dealership doesnt get you a waterthermoswitch instead), and the solenoid is around $50. they are both kind of in the same place, and the same things need to be taken off to get to them.

good luck!