DTC P0106 - Baro circuit problem.
The PCM monitors differences between intake manifold vacuum and atmospheric pressure at idle. This signal is from the EGR boost sensor and is switched by the EGR boost sensor solenoid. When the difference is lees than 1.9 in. Hg, it will set DTC P0106. Possible causes:
Here is diagnostic test procedure:
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This is a Paysite
Autozone was partially correct, but your vehicle doesnt have a MAP sensor, it has an EGR boost sensor and boost sensor solenoid.
Here is a test you can do on the boost solenoid without a diagnostic level2 scanner:
Remove the EGR boost solenoid. Apply air pressure to port "B" of solenoid valve(see below). Air should flow from port "C" only. Using jumper wires, apply battery voltage to solenoid valve terminals. Apply air pressure to port "A" of solenoid valve. Air should flow from port "B" only. If solenoid fails either test, replace solenoid. (EGR boost solenoid is located next to the air cleaner)
Do this test before replacing anything. IF it passes, and all vacuum lines are ok(no clogs, no cracks or breaks or signs of collapsing), then you will be looking at a faulty PCM. If it is the PCM that is faulty, it will need to be replaced by a dealer as it will need to be programmed with a Mazda scanner.
Sorry, I misread on which you had already tested. To do full test on the boost sensor you have to have a diagnostic scanner Level2 at least, but there are some tests you can do, as well as checking the wiring. Below are the test and wiring diagrams highlighting the boost sensor wiring. While the majority of the time it is a faulty boost sensor there is always a chance of an open/short in wiring harness, so if you can, do the tests you can do to check for open or short in wiring to eliminate that before spending the money on the boost sensor.